What should be paid attention to in the design and selection of high-voltage connectors (top)?

The high-voltage electrical connection system mainly includes high-voltage wiring harnesses and connectors. The electrical connection system accounts for a certain proportion of the vehicle failure report, and the electrical connection has become a weaker link in the high-voltage system.

In the electrical connection system, the quality of the connector is particularly important, which has become a vital factor to ensure the safety and reliability of the electrical connection. When the connector is selected and applied, it needs to be based on the component’s use environment (such as temperature, humidity, altitude, etc.) and installation location (Vibration conditions, volume structure, sealing level requirements), current-carrying characteristics, cost accounting and other reasonable selection of products. The ideal expectation for high-voltage connectors is that the products have a higher level of safety protection, high temperature resistance, large current-carrying, low power consumption, grease resistance, small size, light weight, long life cycle and low cost.

1. Security

The safety protection of the connector mainly refers to the electrical performance meeting the design requirements, such as insulation, withstand voltage, electrical clearance, creepage distance, foolproof, and anti-finger (insulating material around the terminal, higher than the terminal height or the terminal with a plastic cap) design In addition to the above performance, it is necessary to pay attention to the connector HVIL, sealing protection, and EMC performance during application.

1) High Voltage Interlock

The high-voltage interlock uses electrical signals to confirm the integrity of the high-voltage system connection, and can also be used as a cover open detection.

When designing high-voltage connectors, consider the high-voltage safety protection during plugging and unplugging. For example, when disconnecting, the HVIL is disconnected first, and then the high-voltage terminals are disconnected; the opposite is true when connecting. HVIL connectors generally have a built-in type and an external type in structural design . Because the built-in type is compact and small in size, the built-in type is commonly used at present, and the high-voltage interlock circuit is installed between the high-voltage terminals.

In applications, some built-in connectors lack the CPA (Connector position assurance) of the interlocking device. If the connector structure is not well designed, under certain harsh conditions, some suppliers’ products will cause the displacement of the interlocking device. The discontinuity of the interlock signal brings unnecessary problems to vehicle debugging and safe driving.

EV High Voltage Connector 3 Pin Plug 35A Straight Metal Shield Plug 3.6mm HVIL Series

Figure 1 built-in type high-voltage interlock connector

In the actual use process, HVIL loop is mainly detected by signal (such as level, PWM signal) injection method, and the failure mode mainly considers HVIL circuit fault short-circuit (including short-circuit to power supply and ground. Level detection is used. The system may not be able to Risk of correct judgment) or disconnection (the product must ensure that the interlock device does not move).

In addition, the connector HVIL device contact resistance and wiring harness loop resistance should be considered when the connector is selected and designed to avoid HVIL detection failure due to signal voltage drop.

2) Protection level requirements

High-pressure connector sealing generally requires at least IP67, and even IP6K9K is required in the selection of some special occasions in the car to ensure that the use requirements are met even during high-pressure washing.

The current product protection requirements and verification methods mainly refer to GB4208, and the parts or connectors are placed at a depth of 1m in the water tank to detect whether the protection level IP67 is passed , but in actual use, whether this can simulate the performance of the vehicle The actual working conditions are debatable.

The actual working conditions of the vehicle need to experience fatigue loads and face the problem of material aging (see Figure 2). For example, long-term exposure to vibration conditions; extreme weather conditions, extreme cold and extreme heat; when wading, the water contains other impurities and needs to deal with corrosive conditions. In order to ensure the product performance throughout the life cycle, in actual use, it is important that the seal is good or bad when the vehicle is approaching the end of its life.

The-harsh-environment-of-the-vehicle

Figure 2  The-harsh-environment-of-the-vehicle

he water-dust and dust-proof test of the connector in the laboratory cannot fully simulate the actual environment of the vehicle connector. The connector product is tested for mechanical fatigue, vibration, thermal shock, salt spray, etc., and then tested for IP67, which can estimate the sealing performance of the system at the end of the life as completely as possible.

In addition, it is worth noting that the sealing material is generally made of rubber, which itself faces life degradation. At present, there is a lack of effective risk reports in the application of connector products. In the system design, it is also necessary to consider how to prevent problems caused by the life degradation of the sealing material.

If the sealing performance can be guaranteed during the whole life cycle of the product, the following points should be considered in the application design of the connector sealing: between the connector and the component (mainly involving the control of component structure design), between the connector and the cable (the product guarantees the seal The position of the ring does not move and the assembly accuracy is controlled during the production of the wiring harness), between the male and female ends of the connector (the product structure process and the integrity of the assembly).

3) EMC

As new energy vehicles use a large number of power electronic devices, the electromagnetic field generated by high voltage and large current will cause electromagnetic interference to other communication equipment, and the whole vehicle and parts must have the ability to resist interference and radiation.

When designing a high-voltage electrical connection system, the connector is required to have a 360°shielding layer and effectively connect to the cable shielding layer. The shielding layer covers the entire length of the connector to ensure sufficient shielding function and minimize the resistance between the shielding interfaces. During the product life cycle, the shield connection contact resistance is less than 10mΩ.

For high-voltage connectors made of plastic, the shielding must be realized with a metal surface.

What should be paid attention to in the design and selection of high-voltage connectors (below)?

Click to see what should be paid attention to in the design and selection of high-voltage connectors (top)

2. Connector temperature resistance and power consumption

If the connector (mainly the contact part) exceeds the specified operating temperature limit, the connector will reduce its safety characteristics due to heat, or even fail and be damaged. The main reasons for the increase in temperature of the connector are as follows:

1) Environmental factors, the layout position is easily affected by high temperature or is in a sealed cabin where heat is concentrated. If the layout position cannot be avoided, the temperature resistance of the connector should also be considered when selecting (such as Table 1).

standard Maximum operating temperature range Class level
Technical requirements for high-voltage and high-current wiring harnesses and connectors for electric vehicles -40℃~125℃ T3
SAE_USCAR_37 -40℃~175℃ T5
LV215 -40℃~150℃ /

Table 1 Connector operating temperature range

2) The connector heats itself, and the main influencing factors are heat dissipation of the contact resistance of the mating contact or poor crimping.

An important measure of the electrical performance of a connector is the contact resistance between the connectors. The smaller the contact resistance, the smaller the voltage drop, which means the lower the electrical loss, and the lower the temperature rise, and the higher the connection terminal Service life.

After the contact is heated, the plating layer will be affected, or an insulating film layer will be formed in the contact area, which will increase the contact resistance, further aggravate the temperature rise, and form a vicious circle.

If the connector is heated beyond the limit, the wiring harness will be burnt when the thermal failure is serious, and the insulating material will be chemically decomposed, which will reduce the insulation performance. In severe cases, the positive and negative poles of the connector may break down and short-circuit after the insulation material is thermally melted.

According to the Volkswagen VW80834 standard, the contact resistance of the connector cannot exceed the limit in Table2:

Cable cross-sectional area mm² Crimping resistance Contact resistance (total resistance, including crimp resistance)
Unused mΩ After aging mΩ Unused mΩ After aging mΩ
2.5 0.17 0.35 1.17 2.34
4.0 0.11 0.22 0.72 1.44
6.0 0.09 0.18 0.68 1.36
16 0.05 0.1 0.43 0.86
25 0.035 0.07 0.40 0.80
35 0.029 0.059 0.39 0.78
50 0.025 0.05 0.36 0.72

Table 2 Connector contact resistance range

After the connector cable is crimped completely, the contact resistance calculation formula is as follows:

Rtotal=Rcrimp1+Rcontact+Rcrimp2

Schematic-diagram-of-connector-contact-resistance

Figure 1 Schematic diagram of connector contact resistance

a) Generally speaking, the crimping of the wiring harness is outsourced to the optional connector manufacturer, which can better guarantee the crimping reliability of the connector. In practical applications, the thermal failure of the connector is mostly due to poor crimping of the wire harness, such as insufficient crimping ratio, resulting in flash crimping, or excessive crimping ratio, resulting in incomplete crimping.

Cable cross-sectional area mm² Pulling force N
2.5 200
4.0 310
6.0 450
16 1500
25 1900
35 2300
50 2800
70 3400
95 4200

Table3 Crimp pull force strength requirements

b) The interface structure of the connector, such as the material/plating type and its purity, thickness, geometry, etc. determine the performance of the connector, including contact resistance, insertion force and insertion life.

The structure of the high-voltage connector terminal contact piece mainly includes split type, crown spring type, torsion spring type, strap type, etc. Different structural forms determine the electrical contact mode (surface contact, line contact and multi-point contact). ), which form to choose depends on the application of the connector. For frequently pluggable connectors, according to the principle of parallel shunting, the number of current-carrying bridges is used to achieve the purpose of reducing contact resistance.

Connector plating generally chooses silver with low contact resistance (as shown in Table 4). The thickness of the plating of different manufacturers’ products is different (the coating is too thin and wears badly, and the adhesion of too thick coating is insufficient). The selection should be based on different applicable occasions. Such as indoor/outdoor, frequent plugging and unplugging, etc.

For example, for charging connectors, the laboratory plug-in test can meet the goal of 10,000 times stipulated by the national standard. However, under the actual conditions of outdoor use, the first environmental conditions faced are worse than those of the laboratory (such as humidity, heat, dust, etc.); secondly, personnel operation Whether the specification is subject to random uncertainty. If used or maintained improperly, the local plating of the charging connector will be severely worn and “copper leakage” will occur, and copper rust will occur during use, resulting in a reduction in the effective current-carrying surface/point.

material Conductivity m/Ωmm² Resistivity Ωmm²/m
copper 57 0.017
tin 9 0.110
silver 62 0.016
gold 41 0.024
nickel 14 0.07

Table 4 Conductive properties of metal materials

In addition, in the application of connector selection, attention should be paid to the structure of the connector terminal. If the plug-in terminal is connected at a 90° right angle, the screw connection structure should be avoided. With this structure, the thread tooth pattern matching accuracy is very tight, but in the process of thread processing and wire harness assembly, incomplete connection and contact cannot be avoided. Especially for high-current terminal connections, in long-term use, the terminal thread teeth will be locally overheated, and the connector faces the risk of thermal failure.

Regarding this point, you can also refer to the VW80304-2013 standard formulated by Volkswagen, which stipulates that the cable outlet is 180°, 90°, and the right-angle 90° method does not allow threaded connection.

3. Connector life and cost

For connector performance and life requirements, the Volkswagen standard stipulates: Passenger car development projects must guarantee a full-featured life cycle: at least 15 years or 300,000Km (≥8000h action+30000h charging), and commercial vehicles must guarantee at least 15 years or 1000000Km.

In the connector selection process, product cost should not be the first consideration. Only on the basis of meeting performance requirements can it be possible to reduce costs and increase efficiency, unless it is willing to sacrifice the reliability of the vehicle’s high-voltage electrical connection.

Of course, in order to ensure product performance, excessive selection of structure and specifications should also be avoided in the selection, which will increase the cost of the product.

To sum up:

High-voltage electrical connection systems involve electrical architecture and safety, and connector products are related to the development of the entire industrial chain.

The performance of the product is determined by the structure and material of the product. After the product structure is optimized to the extreme, the competition of product performance is the competition between basic materials and physical research.

In product selection and application, if you do not grasp the interface material of the connector and understand the failure mechanism of the connector, it is impossible to scientifically evaluate the reliability of the connector.

Global standards for high-voltage connectors

Global standards for high-voltage connectors

In the International Standard Classification, high-voltage connectors relate to road vehicle devices, radiation measurement, electrical components, pipe components and pipes, floor treatment equipment, switchgear and controllers, mining equipment, transformers, reactors, inductors, road vehicle internal combustion engines, Nuclear energy engineering.

In the Chinese standard classification, high-voltage connectors relate to automotive electronics, electrical equipment and instrumentation, reactors, nuclear power plant safety power distribution equipment, hoses, tape, tape, household cleaning, whole containers, electronics, electrical equipment, high-voltage switchgear , Inductors, transformers, connectors, special equipment for coal mines, transformers, low-voltage power distribution appliances, intake and exhaust and fuel supply systems, general nuclear equipment.

The State Administration for Market Regulation and the National Standardization Administration of China, standards for high-voltage connectors

  • GB/T 37133-2018 Technical requirements for high-voltage and high-current wiring harnesses and connectors for electric vehicles

State Administration of Quality Supervision, Inspection and Quarantine, standards for high-voltage connectors

Standards on high-voltage connectors

  • SFS 2663-1975 Structure test of high voltage connector

German Institute for Standardization, standards for high-voltage connectors

  • DIN EN 1829-2-2012 High-pressure water spray machinery. Safety requirements. Part 2: Hoses, hose lines and connectors
  • DIN EN 62271-209-2008 High-voltage switchgear and controller. Part 209: Cable connectors for gas-insulated metal-enclosed switchgear with rated voltage higher than 52kV. Liquid-filled and extruded insulated cables. Liquid-filled and dry type Cable termination
  • DIN EN 1829-2-2008 High-pressure water spray machinery. Safety requirements. Part 2: Hoses, hose lines and connectors

American Society of Motor Vehicle Engineers, standards for high-voltage connectors

  • SAE/USCAR-37-2008 High voltage connector performance. Supplement to SAE/USCAR-2
  • SAE J 1949-1988 Road vehicle high pressure fuel injection pump end connector 60Deg female cone wheel

Canadian Standards Association, standards for high-voltage connectors

  • CSA C227.4-06 UPD 2-2007 Three-phase, gasketed distribution transformer with separable insulated high-voltage connectors
  • CSA C227.4-06 UPD 1-2007 Three-phase, gasketed distribution transformer with separable insulated high-voltage connectors
  • CSA C227.3-06-CAN/CSA UPD 1-2007 Low-section, single-phase, gasketed distribution transformer with separable insulated high-voltage connectors
  • CSA C227.4-06-2006 Three-phase, mated distribution transformer with separable insulated high-voltage connectors. 2nd edition
  • CSA C227.3-06-CAN/CSA-2006 Low-section, single-phase, gasketed distribution transformer with separable insulated high-voltage connectors. Fourth edition

European Committee for Electrotechnical Standardization, standards for high-voltage connectors

  • EN 62271-209-2007 High-voltage switchgear and control equipment. Part 209: Rated voltage>52kv gas isolation metal-encapsulated switch cable connector. Liquid-filled and extruded insulated cables. Liquid-filled and dry-type cable terminals

U.S. Defense Logistics Agency, standards for high-voltage connectors

  • DLA DSCC-DWG-89055 REV C-2006 No. 8 jack contact high voltage direct welding connector

Industry standards-coal, standards for high-voltage connectors

MT/T 947-2005 Flameproof high voltage cable connector for coal mine

American Institute of Electrical and Electronics Engineers, standards for high-voltage connectors

  • IEEE C57.12.23-2002 Underground, self-cooling single-phase distribution transformers with separable insulated high-voltage connectors: high-voltage 25000V and below, low-voltage 600V and below, 167kVA and smaller transformers
  • IEEE C57.12.23-1992 Underground type, self-cooling single-phase distribution transformer with separable insulated high-voltage connectors. High voltage (34,940GrdV/1400V) and below and low voltage (240/120V, 167kVA)
  • IEEE C57.12.26-1992 Separate self-cooling three-phase distribution transformer installed on the base used with separable insulated high-voltage connectors. (34500GrdV/19920V and below, 2500kVA and below)
  • IEEE 592-1990 Exposed semiconductor sheath of high-voltage cable joints and separable insulated connectors
  • IEEE N 42.4-1971 High voltage connectors for nuclear instruments
  • IEEE/ANSI N 42.4-1971 American National Standard for High Voltage Connectors for Nuclear Instruments

American National Standards Institute, standards for high-voltage connectors

  • ANSI C57.12.25-1990 Transformer. The interval type self-cooling single-phase distribution transformer installed on the base with detachable insulated high voltage connector. The high voltage is not more than 34500Y grounding/19920V, the low voltage is 240/120V, and the capacity is not greater than 167 kVA. Requirements

British Standards Institute, standards for high-voltage connectors

  • BS 6553-1984 Fuse Connector Selection Guide for High Voltage Fuses for Transformer Circuit Equipment

International Electrotechnical Commission, standards for high-voltage connectors

  • IEC 60498-1975 High voltage coaxial connectors for nuclear instruments

 

Design scheme of high voltage interlock

Definition of high voltage interlock:Check the integrity and continuity of the loop of the entire high-voltage system through the low-voltage signal, identify the abnormal disconnection of the loop, and disconnect the control electrical components of the high-voltage input in time.

Design scheme of high voltage interlock

  1. The HVIL circuit must be able to effectively, real-time and continuously monitor the on-off condition of the entire high-voltage circuit,
  2. All high-voltage connectors should be equipped with mechanical interlocking devices, and when the high-voltage connectors are disconnected, HVIL is disconnected first; when connected, HVIL is connected later.
  3. All high-voltage connectors cannot be connected or disconnected under non-human conditions
  4. The high-voltage interlock circuit should be equipped. Under special circumstances, the HVIL circuit can be directly detected through the BMS, and the high-voltage circuit can be directly disconnected.
  5. When an abnormality in the HVIL is recognized, the vehicle must give an alarm, such as instrument indicator lights, sound, light, etc. to remind the driver.

Design scheme of high voltage interlock

Scheme 1 is shown in Figure 1. The thick solid line represents the 12V low-voltage power circuit in the detection circuit, and the dashed line represents the HVIL monitoring circuit. The HVIL monitoring circuit of high-voltage components (DCDC, PTC, compressor, etc.) is controlled by VCU, and the low-voltage control output terminals of the three high-voltage relays in the battery pack are directly grounded through detection point 1 to monitor the working condition of the emergency power-off circuit. The high-voltage HVIL circuit of the motor and DCU is directly connected to the control coil of the low-voltage relay 2, and the other end is grounded.

Design scheme of high voltage interlock

Design scheme of high voltage interlock

Figure 1 Option One

working principle

When an emergency disconnection occurs, monitoring point 1 directly feeds back the detection result to the BMS, and the BMS disconnects three high-voltage relays. When the motor and the high-voltage connector of the DCU are connected, the low-voltage relay 2 is turned on, and the 12V of the BMS is turned on. When the high-voltage connector is not connected, the power of the BMS is disconnected through the low-voltage relay 2 to realize the power-off function. Other high-voltage components detect their respective HVIL states through detection points 3, 4, and 5, and feed them back to the VCU.

 Pros and cons

Each high-voltage component has its own HVIL test, if a fault occurs, it is easy to troubleshoot. The HVIL status of the motor and DCU can directly determine whether the BMS is working and reduce the risk. The disadvantage is that the low-voltage relay is added to control the BMS power supply, which makes the wiring harness design more complicated and the total weight of the wiring harness increases. In addition, if the low-voltage relay 2 is stuck, the VCU can only pass the BMS Indirectly disconnect high-voltage components.

In the second scheme (as shown in Figure 2), the thick solid line represents the 12V power line, and the dotted line represents the HVIL detection circuit. Compared with the first scheme, except for the motor and DCU, other high-voltage components are connected in series, and only one monitoring point is needed. In addition, the low voltage relay 2 is missing.

Design scheme of high voltage interlock

Design scheme of high voltage interlock

Figure 2 Scheme two

working principle

When encountering an emergency power failure, the detection point 1 sends the detection result directly to the BMS, and the BMS directly disconnects the high-voltage relay; the motor and DCU detect the connection of the high-voltage connector through the detection point 2 and send it to the VCU. If any connector is not properly connected, the VCU detection result controls the BMS, which makes the BMS control the high-voltage relay action to achieve power-off. The HVIL status of the other three high-voltage components is determined by monitoring point 3. If one is not connected, the VCU disconnects the high-voltage relay by controlling the BMS.

Pros and cons

Compared with solution one, solution two has advantages in wiring harness design and wiring harness quality, but if there is an abnormality in detection point 3, it is difficult to determine which high-voltage component has an abnormal HVIL.

General requirements for high voltage interlock circuit HVIL

In the near future, I will pay more attention to the issue of battery high voltage safety. Here are some requirements for high-voltage interlocking. These requirements are general requirements. For these requirements, each manufacturer will have their own different implementation methods. For example, if the barrier/enclosure permits direct access, individuals can only open or remove it using tools or maintenance keys, or there is a method to disconnect the B-level voltage at certain points, such as through an interlock.” Interlock here generally refers to High Voltage Interlock Loop (HVIL), which detects the electrical integrity or connectivity of high-voltage components, wires and connectors through low-voltage circuits, recognizes abnormal disconnection of the circuit, and disconnects the controller at the high-voltage input in time.

When HVIL fails, make sure to safely power off the high-voltage system in an appropriate manner. Before resolving the fault, refrain from powering on the high-voltage system, while simultaneously triggering the corresponding DTC. When disconnecting the high-voltage module from the high-voltage circuit, exercise caution regarding the charging of capacitive loads and high-voltage cables to prevent electric shocks to operators. During normal vehicle operation, prevent electric shocks caused by improper operation, vehicle vibration, product aging, and local heating and arcing caused by line wear.

HVIL Design Requirements

1) The functional safety level of HVIL-related modules in the controller should reach ASIL C

2) HVIL should include a signal generator and 2 signal detection devices

3) It must be able to continuously and real-time monitor the on/off of the entire loop

4) Users cannot open or separate all high-voltage connectors of the HVIL circuit without tools or without doing so unconsciously.

5) All high-voltage connectors of the high-voltage circuit should have mechanical interlocking devices. The high-voltage connectors can only be opened when the HVIL circuit is disconnected first.

6) The HVIL circuit should have a safety redundancy design, that is, the failure of a key component will not seriously affect the misjudgment of the high-voltage circuit monitoring function

7) Under special circumstances, the HVIL circuit can be detected directly through the HCU or BMS, and the high-voltage circuit can be directly disconnected.

 

Diagnostic Function Requirements

The HVIL related controller should diagnose the following faults

1) The circuit is disconnected

2) Short circuit to ground

3) Short circuit to 12V power supply

4) Short circuit

5) The loop impedance becomes larger

Signal Source Requirements

1) HVIL signal source voltage is generally 5V

2) HVIL and 12V power supply are short-circuited, the signal source cannot fail, and it has reverse protection

3) HVIL wiring harness cannot have branch crimp contact points

4) When the voltage of the 12V lead-acid battery drops, such as about 10V. It is also necessary to protect the HVIL signal source to have a stable output.

High Voltage Connector Requirements

1) The high voltage connector needs to integrate the interlock function

2) When the high voltage connector is disconnected, HVIL is disconnected first; when connected, HVIL is connected later, some designs are connected at the same time

3) The contact resistance of the high-voltage connector after joining meets the “Technical Conditions of Automotive Wire Harness Connectors”

4) When the interlocking wiring harness is arranged, it should be led out from the low-voltage interface of the high-voltage components and separated from the high-voltage wiring harness.

5) Usually, connectors are crimped, plugged and unplugged, and they typically have angles of 90° or 180°, often featuring built-in interlocking shorting tabs or pins at the harness end or plug-in end. For example, in a relatively common MSD, the HVIL design (yellow dashed frame) in the picture below employs pins.

Hazard Control Strategy

When HVIL recognizes a danger, the entire controller needs to use safety strategies reasonably according to the driving status and the degree of damage caused by the accident at the time of the incident. Here are some common safety strategies:

1) Failure alarm. Regardless of whether the vehicle is driving or not, when HVIL recognizes a danger, it must issue a warning in some form to remind the driver to deal with it in time

2) Cut off the high voltage. When the vehicle is in a stopped state, when HVIL detects danger, it needs to tell the system controller to disconnect the high voltage.

3) Reduced power operation. When identifying a danger during driving, it is not possible to immediately disconnect the high voltage. First, the control system issues a reminder or alarm to alert the driver of the abnormality. Subsequently, the system reduces the operating power of the motor and the speed of the vehicle, allowing the high-voltage system to operate under a lighter load. This provides the driver with a certain amount of time to pull over and stop, facilitating the next step of failure analysis.

There are many ways to realize HVIL in electrical design, and the realization of each way needs to consider the interrelationship between various high and low voltage devices, and comprehensively consider the overall requirements of the system.

New energy electric vehicle high-voltage system connection relationship

In order to understand the connection relationship between the various systems of the new energy electric vehicle, a simple logic diagram is now given to deepen the understanding of each system.

High-voltage system components connection logic diagram

New energy electric vehicle high-voltage system connection relationship

New energy electric vehicle high-voltage system connection relationship

It is recommended to look at it for yourself first, think about the logical connection between them, and then look at the following specific introduction.

1. Power Battery

Power battery is an energy supply device in electric vehicles, which needs to provide energy for all systems of the vehicle. When the power is consumed, you also need to charge him. Therefore, its energy flow has both outflow and inflow.

2. High voltage distribution box (PDU)

PDU can be considered as a place for power transfer and distribution, and each component in the high-voltage system needs it for power distribution. Such as high-pressure compressor, PTC, motor controller, etc.

3. service switch

The service switch is located between the power battery and the PDU, which is a necessary component. When the power battery is repaired, it can be used to cut off the high-voltage power of the vehicle to ensure the safety of repairs.

MSD Connectors 500A Waterproof IP67 2 Pin Orange Plastic Plug

 

high-voltage service switch

4. Motor controller and drive motor

The motor controller converts the high-voltage direct current from the PDU into three-phase alternating current and supplies it to the drive motor.

The drive motor converts electrical energy into mechanical energy to provide power for the vehicle to travel. At the same time, the drive motor can also convert the mechanical energy (such as braking efficiency) generated during driving into electrical energy, and finally send it to the power battery to supplement the electrical energy.

5. Fast charging port

The power of the fast charging port is high-voltage direct current, which can be directly sent to the power battery for charging through the PDU without processing.

6. Slow filling

The power of the slow charging port is high-voltage alternating current, which needs to be converted through the OBC unit in the two-in-one controller, or OBC (there is no two-in-one controller, OBC and DC/DC are separated). The converted high-voltage direct current is charged through the PDU to charge the power battery.

7. DC/DC

In order to achieve the electric balance of the whole vehicle, the power battery needs to provide the power supply of the electric appliances of the whole vehicle, and at the same time, it can charge the battery. However, the power of the power battery is high-voltage electricity, so it is necessary to convert high-voltage direct current into low-voltage direct current through a DC/DC device.

 

The composition and role of high-voltage systems in new energy electric vehicles

This article mainly introduces the composition and role of high-voltage systems in new energy electric vehicles

The composition of the high-pressure system

In the new energy electric vehicle, the parts with high voltage of the whole vehicle include power battery, drive motor, high-voltage distribution box (PDU), electric compressor, DC/DC, OBC, PTC, high-voltage wiring harness, etc., these components It forms the high-voltage system of the whole vehicle, in which the power battery, the drive motor, and the high-voltage control system are the three major components of the new energy electric vehicle.

1.Battery pack and power battery management system BMS

Different from traditional fuel vehicles, the power source of new energy electric vehicles is the power battery, not the engine. Because pure electric vehicles use electric energy directly, they do not need to burn the fuel and discharge the emissions into the atmosphere like traditional fuel vehicles. Therefore, in order to reduce environmental pollution, the development of new energy vehicles is actively supported by the state.

The voltage of the new energy power battery is generally 100~400V, and its output current can reach 300A. The capacity of the new energy power battery directly affects the mileage of the vehicle, and also directly affects the charging time and charging efficiency. Lithium-ion power batteries are currently the mainstream. Affected by current technology, most current cars use lithium-ion power batteries.

new energy electric vehicles

new energy electric vehicles

2.Drive motor and motor controller MCU

The motor controller MCU converts high-voltage direct current to alternating current, and performs signal interaction with other modules on the vehicle to achieve effective control of the drive motor. The drive motor converts electrical energy into mechanical energy to drive the car. Unlike traditional fuel vehicles, which convert the chemical energy of fuel combustion into mechanical energy, the engine has a higher working efficiency, which can reach more than 85%. Therefore, compared with traditional vehicles, its energy utilization rate is higher and can reduce the waste of resources.

3.High voltage distribution box

The high-voltage power distribution box is a power distribution device for the high-voltage power of the entire vehicle, similar to the electrical fuse box in the low-voltage circuit system. The high-voltage fuse box PDU (Power Distribution Unit) is composed of many high-voltage relays and high-voltage fuses. There are related chips inside it to realize signal communication with related modules to ensure the safety of high-voltage electricity for the whole vehicle.

high-voltage power distribution box

high-voltage power distribution box

4.Car charger OBC

On Board Charge is a device that converts alternating current to direct current. Because the battery pack is a high-voltage direct current power supply, when using alternating current for charging, the alternating current cannot be directly stored by the battery pack. Therefore, an OBC device is required to convert the high-voltage alternating current to high-voltage direct current to charge the power battery.

5. DC/DC

In new energy vehicles, DC/DC is a device that converts high-voltage direct current to low-voltage direct current. There is no engine in new energy vehicles, and the source of electricity for the whole vehicle is not all generators and batteries, but power batteries and batteries. Since the rated voltage of the vehicle’s electrical appliances is low voltage, a DC/DC device is required to convert high-voltage direct current to low-voltage direct current, so as to maintain the balance of vehicle power consumption.

DC/DC device

DC/DC device

 

6. OBC and DC/DC two-in-one controller

Affected by the layout of the whole vehicle, many cars now combine the two components of OBC and DC/DC into one component. This component is usually called a two-in-one controller. Its function is actually the two components of OBC and DC/DC. Combination of functions.

7.  Electric compressor

The compressor of the traditional car is attracted by the electromagnetic clutch of the compressor, which prompts the engine to drive the compressor to operate. An electric vehicle has no engine, and its compressor is directly driven by a high-voltage power source. In order to distinguish it from the compressor of the traditional car, the air-conditioning compressor on the electric car is called an electric compressor here.

8. PTC heater

The heat source of the air conditioning heating system on traditional vehicles is the heat of the coolant introduced into the engine after cooling. This does not exist in new energy vehicles. Therefore, a special heating device is required. This device is called an air conditioner PTC. The function of PTC (Positive Temperature Coefficient) is heating. When the temperature is low, the battery pack needs heat to work normally. At this time, the battery pack PTC is required to preheat the battery pack.

9. High voltage wiring harness

The high-voltage wiring harness connects the various components of the high-voltage system as a medium for high-voltage power transmission. Different from the low-voltage wiring harness system, these wiring harnesses are equipped with high-voltage electricity, which greatly affects the stability of the high-voltage system of the vehicle. The safety of high-voltage wiring harness design is our main consideration.

 

High voltage interlock connector in BMS

The high-voltage interlock function is also an important function on the BMS, and other high-voltage controllers will also have this function, such as VCU, etc.; its function is to detect the connection status of the High Voltage Interlock Connector in the high-voltage circuit and identify the high-voltage connector is not connected Or accidental disconnection failure;

As shown in the figure below, the loop of the red line in the figure is the high-voltage interlocking loop, which connects all the relevant high-voltage connectors in the system in series and detects their connection status at the same time.

 

High Voltage Interlock Loop

High voltage interlock connector

The realization of HVIL firstly depends on the structure of the connector itself. The high voltage connector integrates the HVIL interface internally. As shown in the figure below, in addition to its own high-voltage and high-current interface, the high-voltage connector also integrates an HVIL interface; the principle is very simple. The HVIL interface has two PIN pins. When the high-voltage connector is plugged in, the two PINs become short-circuited. ; When the high-voltage connector is disconnected, these two PIN pins are open. The HVIL function is realized by detecting the on-off of these two PIN pins.

HVIL connector

HVIL connector

Similarly, the high-voltage maintenance switch (MSD) also integrates the HVIL interface, as shown in the figure below.

There is a time difference between the HVIL interface in the high-voltage connector and the high-voltage high-current interface when it is inserted or unplugged, as shown in the figure below; when the connector is inserted, the high-voltage terminal contacts first, and the HVIL terminal contacts later, the time difference is Δt1; When the device is pulled out, the HVIL terminal is disconnected first, and the high-voltage terminal is disconnected afterwards. The time difference is Δt2; in this way, the HVIL terminal can ensure that the high-voltage terminal has been reliably connected or the accidental disconnection can be predicted in advance.

high-voltage maintenance

high-voltage maintenance

The above two time differences are generally related to the speed of insertion or removal. I have probably tested it before. Δt1 is about 1s, and Δt2 is about 100ms. The time is not very accurate, but the magnitude is about the same.

Next, a brief introduction to the HVIL detection circuit is generally divided into two types, the DC source scheme and the PWM scheme. As shown in the figure below, the left picture is a simplified diagram of the DC source scheme, and the right picture is a simplified diagram of the PWM scheme. In the left picture, an external DC source is applied to the entire HVIL loop, and the high-voltage connector state is diagnosed by detecting the voltage at V1\V2; in the same way, in the right picture, a controllable switch is introduced, the same Still detect the voltage at V1\V2, but by controlling the switch, two sets of values can be obtained to identify more states;

high-voltage maintenance

high-voltage maintenance

The actual HVIL detection circuit is more complicated. First, determine the type of fault to be detected, and then design the detection circuit according to the type of fault; the types of faults include open circuit, short circuit to ground, short circuit to power, and larger loop impedance.

The high-voltage interlock diagnosis is an important safety mechanism that falls into the safety goal of the BMS. Once a fault is diagnosed, the BMS must enter a safe state. Among them, the whole vehicle scene needs to be subdivided. The safety status is completely different in different scenes; for example, the charging scene, the driving scene, and the startup scene.

to sum up:

This article briefly introduces the concept of HVIL. In most cases, the HVIL circuit is a system circuit. It traverses all the main high-voltage interfaces, and the detection range is defined by the OEM. The difficulty of the HVIL function lies in the processing strategy after the failure is found, which is also the core.

How does the m5 m8 m12 connectors and cables waterproof?

 

How does m5 m8 m12 connectors and cables waterproofing?

Need the m5 m8 m12 connectors and cables waterproofing, We must to   analyse  the connector and wire.

M5,M8,M12 connectors to waterproof, the first solution to the connector structure waterproof.Generally speaking, the waterproof structure of the circular connector is usually built with a circular plastic washer at one end of the connector. When the connector is inserted, the built-in plastic washer is squeezed to ensure the waterproof effect of the connector insertion position.But that alone will only get you up to IP67.How do we need to achieve the waterproof level of IP68 when the connector is inserted and fitted? This requires special structural design, which will not be discussed here.

4 Pin M8 Connector Female Plug Straight Screw-joint Unshielded

If the M5, M8, and M12 connectors are waterproof without being plugged in, how should they be designed?
In this case the splitter end (mounted on the device) and the wire end (detached from the device and used to plug in the device).Actually board end and line end are waterproof with same kind of method, use dustproof cover namely.It’s just a waterproof plastic gasket built into the dust cap.The waterproof principle is the same as that when the plug and socket are plugged, it is through squeezing the waterproof washer, so as to achieve the purpose of waterproof.

 

The waterproof principle of the M5 M8 M12 connector has been said, so how to make the connection line waterproof?
If the M5 M8 M12 connector is waterproof, the M5 M8 M12 connector must be injection molded, so that the connector and the connector can be tightly combined.If the plastic assembly and metal assembly, the tail will have gaps, not waterproof effect.

 

M5, M8 and M12 injection molding type connection line can generally reach the waterproof IP67 or so, if the waterproof level to reach IP68, according to different wire, use different injection material formula, make the injection molding compound and wire completely integrated, in order to achieve the waterproof LEVEL of IP68.

What Do You Need to Know About the M12 8-pin Connector?

If you want to obtain safe, reliable, sealed, and waterproof power and signal connections between actuators, sensors and industrial equipment, robots, and automation equipment, IP67 circular waterproof M12 8 pin connector pinout is a better choice. The M12 connector is a component frequently touched by electronic engineering professionals and an indispensable component in electronic products. The following article will introduce you to the knowledge you must know about M12 8 pin connectors.

Firstly, I will introduce you the coding type of M12 connector. Common coding types of M12 connectors: A coding, B coding, C coding, D coding, X coding, S coding, T coding, L coding and P coding.

M12 Connector Pinout and Coding Structure

1. M12 Connector A Code Male and Female

Application: M12 A coded male connector is used for device network, IO link and Profibus actuator sensor plug connection.

2. M12 Connector B Code Male and Female

Application: Fieldbus connection of Profibus and Interbus.

3. M12 Connector C Code Male and Female

4. M12 Connector D Code Male and Female

Applications: Industrial Ethernet, Profinet, Ethernet/IP and EtherCat.

5. M12 Connector X Code Male and Female

Application: Cat6A, high-speed 10Gbit rugged industrial Ethernet.

6. M12 Connector S Code Male and Female

Application: motor, frequency converter, electric switch, power supply PSU, 620V, 12A

7. M12 Connector T Code Male and Female

Application: Fieldbus components, passive distribution boxes, motors, power supply PSU, 63V, 12A.

8. M12 Connector L Code Male and Female

9. M12 Connector P Code Male and Female

M12 8 Pin Connector Pinout and Coding Structure

Next, I will introduce you to the M12 connector 8 Pin Male Connector Pinout and coding structure. M12 8-pin connector has two common coding types: A code and X code.

  1. M12 A coded 8 Pin Male Connector Pinout and coding structure

2. M12 A coded 8 Pin Female Connector Pinout and coding structure

3. M12 X coded 8 Pin Male Connector Pinout and coding structure

4. M12 X coded 8 Pin Female Connector Pinout and coding structure

The M12 8 Pin Connector Wire Color Code

 

M12 Connector Part Number Coding Rule for Ordering

M12 8-pin Connector Features Overview:

The connector is designed for a variety of different industrial application environments,   provides a variety of material connection cable options. Has the following characteristics:

  1. Very strong acid, alkali, chemical cleaning agent/reagent performance.
  2. Resistance to welding sparks, frequent torsion and bending.
  3. Reduce wiring so that the equipment can be put into operation quickly.
  4. Reduced downtime and maintenance time.
  5. Resistance to oil, coolant, lubricant and emulsion.
  6. Suitable for the harshest environments such as petroleum, chemical industry, steel, electric power, automobile manufacturing, etc.
  7. Good mechanical and electrical properties ensure stability and reliability.
  8. The shielded connector has good anti-electromagnetic interference performance.

Renhotec  is a professional connector manufacturer of precision connectors and wiring harnesses integrating R&D, production, sales and service. It has 16years of expertise in high-quality RF connectors. The product variety has more than 20,000 kinds , Fully able to meet the needs of various high-end customers. Feel free to contact us!