Comparison and selection of electric vehicle charging solutions
This article attempts to analyze various charging schemes for electric vehicles in order to find a practical and feasible charging scheme for electric vehicles in China.
1. The role and function of the charging station
Generally speaking, the charging station has two functions: normal charging and emergency charging.
1. Normal charging: It is equivalent to that fuel-fueled vehicles must often go to the gas station to refuel, and the daily charging of electric vehicles can be completed by the charging station. But in fact, there are many disadvantages of normal charging in charging stations: household electric vehicle power batteries 40-60AH, working voltage in the range of 300V-400V, endurance capacity in the range of 120-150km, commercial electric buses (public transportation or intercity transportation), power battery 400 -600AH, working voltage 350V-400V, its endurance 300-400km, that is to say, whether it is a household electric car that travels 150km on a single charge, or an intercity bus that lasts 400km on a single charge, it must be charged every day, so it cannot be applied For fuel-fueled vehicles, the charging station is selected as the normal charging method for electric vehicles. After all, fuel-fueled vehicles can continue for 400-500km after one refueling. It usually takes 5-7 days to refuel, and the refueling time is short. You have to go to the charging station every day for charging, and the charging time is more than 1 hour, which is unacceptable to most car owners. In addition, in order to be fully charged within 1 hour, the "fast charging mode" must be used, that is, charging with a current of ≥1.0C. This charging mode has a high safety risk, and the charging cannot exceed 80%, and we know that electric vehicles now The electronic drift inlay characteristics of commonly used power lithium batteries show that the key point to improve the output of the battery is to charge to a small current of 80% -100% of the final charging interval. The fast charging mode of the charging station does not provide small current slow charging, but fast charging Up to 80% can not get 80% of the power. Some data show that only 50% -60%. Then, the normal slow charge battery with a range of 150km, and the normal charging station with fast charging, the endurance will not exceed 100km! This shows that even if electric vehicles are driven for short distances in urban areas, it may happen that charging stations will charge one or more times per day. As a result, the applicability of electric vehicles will be greatly reduced. It can be concluded that the fast charging station cannot independently undertake normal charging tasks.
2. Emergency charging: When the electric vehicle occasionally lacks power and cannot be plugged in, the fast charging is implemented for a short time, so that the electric vehicle can quickly obtain the ability to extend the range of 30-50km. Obviously, this is the main function of the charging station. As an emergency system, a small number of fast charging stations and mobile fast charging vehicles must be built in advance.
2. Peak-valley charging of electric vehicles
According to the National Development and Reform Commission's new energy vehicle industry plan, China's new energy vehicles have reached 5-10% of production in recent years. In 2009, the annual output of vehicles reached 13 million vehicles, and 10% of them were 1.3 million vehicles. The social ownership of electric vehicles will reach 6-7 million vehicles, the required slow charging power is 20-30 million kilowatts, and the fast charging power can reach 100-120 million kilowatts. In 2008, the country's total installed power capacity reached 100 million kilowatts. The charging power of electric vehicles is equivalent to 15% of the national installed capacity. If a fast charging station is used for charging during peak periods, it may result in a power shortage of hundreds of billions of kilowatts. On the contrary, if there are hundreds of millions of installed capacity, there will be 1/3 of Gudian installed capacity in the valley period, which is 2-250 million kilowatts. China's power grid is dominated by thermal power, and its peak shaving capacity is poor. How to ensure the basic power load during the valley power period is a key factor for improving the quality of the power grid.
The valley period should be selected for electric vehicle charging. Valley electricity usually appears from 11:00 pm to 7:00 the next day. This period is especially suitable for plugging in and charging slowly for 6-8 hours. The charging period coincides with the owner's sleep period. Charging power, the best of both worlds! The normal slow charging of electric vehicles, the charging current should be 0.2-0.3C, which is about 1 / 5-1 / 4 of the fast charging. According to this, the relatively small power intelligent charger for the vehicle is designed, and the AC power supply pile at the night parking lot is used. Completing the slow charging of Valley Power not only saves money, but also ensures the quality of charging, and can also improve the difference between the peak and valley of the power grid.
3. Alternative emergency charging for electric vehicles
If the on-board smart charger is used for the normal charging of electric vehicles, and the slow charging is plugged in during the valley power period, we must find an emergency solution to replace the charging station:
One: battery leasing replacement program, the idea of ​​this program is that the owner of the car buys a car without a battery, and the battery is rented separately. The battery rental company has a certain amount of battery backup, which charges itself during the valley electricity period, and after the electric vehicle battery discharge alarm Go to the battery replacement station to change the battery (like changing the gas bottle), and the replaced battery will be backed up after charging.
The advantage of this scheme is that it can lower the threshold for buying electric vehicles. At the same time, the battery can be charged slowly, without consuming too much time for the owner, but there are three problems: First, the battery company must have twice the number of batteries for electric vehicles. , Otherwise it cannot be recharged by Vale. Secondly, the battery specifications must have good interchangeability. In addition, frequent battery replacement requirements must be considered when designing the vehicle, which will lose a lot of space. At the same time, the owner must change the battery at the battery station every day. Charging at the station is the same, the car owner will be bored!
Second: the charging station + mobile charging car, like road rescue, is handled by a professional company. When receiving a rescue call, it receives a fast charge from the station or an emergency charging on site to charge the car. The disadvantage of this solution is that it is difficult to charge the remote rescue And the one-time investment is large and the rescue is not timely, so it is not suitable for large-scale selection, but a small amount of emergency can be provided.
Third: Self-provided generator plan: The most typical one is the GM Chevrolet Volt. This car is a pure electric vehicle, but it is equipped with a small gasoline generator and a 10L spare fuel tank. The gasoline generator can be started after the vehicle discharge alarm , For the car charger to charge the battery, making the electric car continue to travel 30-50 kilometers (Volt's shortcoming is that the endurance is too small, only 60KM).
It is recommended that electric vehicle manufacturers choose their own gasoline generator solution, and configure a 3KW-5KW fuel generator on a domestic passenger car, and supply a vehicle-mounted 3KW-5KW charger when necessary to charge the power battery during operation. Understand as an alternative hybrid (only electric drive without fuel drive)
4. Conclusion:
1. The electric car is equipped with a 3-5KW car charger with the same power gasoline generator (cost 3-5 thousand yuan). Under normal circumstances, the AC power pile at the night parking lot is used to charge the power battery during the valley power period. When there is a lack of power on the way, many gas stations are used to refuel the generator and self-generation to charge the battery.
2. Commercial buses are equipped with 0.25C car charger, set up AC power piles in the terminal parking lot, and use the car charger to charge slowly during the valley power period, and at the same time set up several fast charging stations in the middle of the path, temporarily use 1-2C to quickly charge Electricity.
Piezoelectric ceramic disc
Quick delivery
High performance
Application: flow meter measurement
There are many kinds of USF used in closed pipeline according to the measuring principle, and the most commonly used are propagation time method and Doppler method. Among them, time difference ultrasonic flowmeter is used to measure fluid flow by the principle that the time difference of sound wave propagating downstream and countercurrent is proportional to the velocity of fluid flow. It is widely used in raw water measurement of rivers, rivers and reservoirs, process flow detection of petrochemical products, water consumption measurement of production process and other fields. According to practical application, time-difference ultrasonic flowmeter can be divided into portable time-difference ultrasonic flowmeter, fixed time-difference ultrasonic flowmeter and time-difference gas ultrasonic flowmeter.
Ultrasonic flow-meters use at least two transducers aligned so that ultrasonic pulses travel across the flow of liquid or gas in a pipe at a known angle to the flow.
Technical data:
Electromechanical coupling coefficient Kp: > 0.62
Dielectric Loss tg δ: <2%
Nominal Piezo discs for ultrasonic flowmeter:
OD14.2*1MHz PZT-51
OD14.6*1MHz PZT-51
OD15*1MHz PSnN-5
OD15*2MHz PSnN-5
OD20*1MHz PSnN-5OD20*2MHz PSnN-5
OD15*1MHz PZT-51
OD15*2MHz PZT-51
OD20*1MHz PZT-51OD20*2MHz PZT-51
Size, Frequency and Electrode on request.
Piezoelectric Discs For Flowmeter Sensor
Piezoelectric Ceramic Disc,Piezoelectric Discs For Flowmeter Sensor
Zibo Yuhai Electronic Ceramic Co., Ltd. , https://www.yhpiezo.com