Hybrid power
The so-called hybrid power generally refers to the hybrid power of oil and electricity, that is, the mixture of fuel (gasoline and diesel) and electric energy.
Hybrid electric vehicle is an auxiliary power-driven vehicle with electric motor as engine.
Hybrid electric vehicles have high fuel economy and excellent driving performance. The engine of hybrid electric vehicle uses fuel, which can reduce fuel consumption with the help of motor when starting and accelerating. Simply put, compared with the same size car, the fuel cost is lower.
Moreover, the motor of the auxiliary engine can generate powerful power at the moment of starting, and the owner can enjoy stronger starting and acceleration. At the same time, it can also achieve higher fuel economy.
At present, there are three main types of hybrid vehicles.
One is the "parallel mode" in which the engine is the main power and the motor is the auxiliary power. This method is mainly driven by the engine and uses the characteristics of the motor to generate powerful power when restarting. When the fuel consumption of the engine is high, such as automatic start and acceleration, the auxiliary drive of the motor is used to reduce the fuel consumption of the engine. The structure of this method is relatively simple, and only the motor and battery need to be added to the car.
The other is the "series-parallel mode" in which the motor is driven only by the motor at low speed and the motor and motor are driven together at high speed. When starting and running at low speed, it is only driven by motor. When the speed increases, the engine and motor effectively share power. This method requires a power sharing device and a generator, so the structure is complicated.
There is also a "series mode" of electric vehicles driven only by motors. The engine is only used as the power source, and the vehicle is only driven by the motor. The drive system only has an electric motor, but it is also a hybrid vehicle, because it also needs to be equipped with a fuel engine.
According to the dependence on electric energy, hybrid power can be divided into mild hybrid power (also known as mild hybrid power, soft hybrid power, micro hybrid power) and so on. ), moderate hybridization, full hybridization (also called full hybridization, strong hybridization, etc. ) and plug-in hybrid.
BSG belt drive start/power generation technology is often used for weak mixing, such as BSG model of Chery A5 (motor 10KW), which usually saves less than 10% of fuel, and the motor does not directly participate in driving, and is mainly used for starting and recovering braking energy.
ISG built-in crankshaft start/power generation technology is often used in medium and hybrid vehicles, such as Buick LaCrosse EcoHybrid (motor 15KW), which usually saves about 20% fuel.
The representative product with strong hybrid power is Toyota Prius (50KW motor), which can save fuel by 40%.
Plug-in hybrid will provide better fuel economy, but it will consume some electric energy, such as the test data of Volkswagen Golf TwinDrive (Motor 130KW), with a fuel consumption of 2.5 kwh per 100 kilometers.
The power system of hybrid electric vehicle is mainly composed of control system, drive system, auxiliary power system and battery pack.
Taking series hybrid electric vehicle as an example, the working principle of hybrid electric vehicle is introduced.
At the initial stage of vehicle driving, the battery is fully charged, and its energy output can meet the requirements of the vehicle, and the auxiliary power system does not need to work;
When the battery charge is lower than 60%, the auxiliary power supply system starts:
When the vehicle energy demand is large, the auxiliary power system and the battery pack provide energy for the drive system at the same time;
When the energy demand of the vehicle is small, the auxiliary power system provides energy for the drive system and also charges the battery pack.
Because of the existence of the battery pack, the engine works in a relatively stable working condition and the emission is improved.
Not all hybrid cars rely on electric engines, batteries and wires. Some vehicles are driven by hydraulic engine, bell line and battery.
Recently, the price of gasoline has reached a record high, which makes consumers standing in front of the gas pump tremble with fear. However, compared with the operators of heavy truck transport fleets, the pain of these consumers can only be regarded as minor pain.
From the point of view of fuel economy, trucks carrying parcels and garbage for us need to bear several adverse effects. Weight is one of the main factors. A fully loaded heavy transport vehicle generally weighs between 14000 and 33000 pounds. In addition to the weight factor, many of these vehicles also have the duty cycle of fuel combustion, and they need to start and stop constantly.
In the past year, UPS has been testing and running hydraulic hybrid vehicles in Michigan.
There are six types of delivery vehicles in the system. The company has also put into use 50 electric hybrid trucks.
Therefore, it will not be surprising to anyone that several largest truck fleet operators have started to chase the trend of hybrid vehicles. FedEx and UPS have added dozens of hybrid trucks to their transportation fleets in the past two years. According to Waste Management, the largest garbage transportation company in the United States, both companies use hybrid trains provided by Eaton Corp
Lynn Brown said that the company is also evaluating a series of hybrid solutions for muck transport vehicles.
However, it may be surprising that FedEx, UPS and waste management companies are considering the types of hybrid systems used in some of the heaviest vehicles. Unlike Toyota Prius, these hybrid systems use electric engines, batteries and wires, but use the combined action of hydraulic pump engines, high-voltage clock lines and batteries to drive vehicles.
This most radical model of hydraulic hybrid power completely gets rid of the traditional mechanical power transmission system. On these vehicles, the diesel engine drives the hydraulic pump engine, which in turn stores energy for the high-pressure accumulator. The accumulator drives the inclined shaft hydraulic pump on the rear wheel, and the engine drives the vehicle. A low-pressure accumulator is used to collect liquid, and then it is sent back to the first hydraulic pump engine, thus forming a complete hydraulic circulation system.
Like the electric hybrid engine, the hydraulic hybrid engine has the ability to provide regenerative braking. Cargo transport vehicles and muck transport vehicles often have to brake. When the vehicle brakes, the hydraulic pump engine will store energy for the high-pressure accumulator. When the truck moves forward again, the energy stored in the accumulator can be used to reduce the load of the diesel engine. When the engine is turned off, such as when the vehicle is running indoors, these energies will also limit the generation of propulsion.
For ordinary consumers or some engineers, in such an increasingly electrified world, hydraulic engine technology seems to be somewhat outdated. The hydraulic pump engine and accumulator can provide a reliable and low-cost way to apply torque and store energy, which is exactly what hybrid vehicles need. Moreover, hydraulic engines have obvious power density advantages over electric systems, at least for now. "Hydraulic engines seem to be very effective, at least for most heavy-duty truck series," commented Dr. John Desico, a mechanical engineer and member of the Advanced Automobile Strategy Society of the Environmental Protection Foundation.
Hydraulic drive mode
Nowadays, there are three main ways of hydraulic hybrid power system, and they are all developing. Researchers from the Office of Transportation and Air Quality (OTAQ) of the US Environmental Protection Agency (EPA) have jointly developed a hybrid power system with Eaton, Southwest Research Institute (SwRI) and other partners. Since June, 2006, the system has been tested and operated on UPS delivery trucks in Detroit. The United States Environmental Protection Agency also signed a separate cooperative research and development agreement with Parker Hannifin, and began to design hydraulic hybrid power.
In some respects, the hydraulic hybrid power system is similar to its matching electric hybrid power system. However, the hydraulic system
The system uses hydraulic pump engine, bell wire and accumulator to generate torque and store energy, instead of generator.
Motives, wires and batteries.
Eaton Company and Parker Hannifin Company have also developed hydraulic hybrid power systems with independent intellectual property rights. Eaton has developed a parallel system assisted by hydraulic starting, but its main propulsion still comes from mechanical power train. Parker Hannifin has developed a new hydraulic hybrid design in the past year and a half, and some load cycle data come from waste management companies. Dr. Joe Kovach, vice president of Parker Hannifin Company and mechanical engineer in charge of innovative design of hydraulic power department, reported that his company will build a muck transport vehicle with the new hydraulic hybrid system later this year.
The disadvantages of large battery size, low energy density and long charging time restrict the development of electric vehicles. The proton exchange membrane fuel cell (PEMFC), which has developed rapidly in recent years, is widely used in electric vehicles because of its high energy conversion efficiency, high energy density, no need to charge and zero emission. At present, the major automobile manufacturers that invest in fuel cell vehicles in R&D include GM, Honda, Ford, Dyke, Renault-Nissan, Fiat, Mazda, Nissan, Toyota, Volkswagen, Mitsubishi and Hyundai. In China, there are SAIC and so on. In addition, Tsinghua University and Beijing Luyuan Company jointly launched a PEMFC fuel cell vehicle prototype, with the fuel cell power of 18kW and compressed hydrogen as fuel.
According to Zhong Zaimin and others' introduction in the article "Control Strategy of Powertrain of Fuel Cell Vehicle", there are three problems in the current automobile fuel cell engine: cold start, slow dynamic response and regenerative braking energy storage, which determines that there must be an auxiliary energy storage element in the powertrain configuration of fuel cell vehicle. In the existing fuel cell concept car, supercapacitors or power batteries are usually used to complete the above auxiliary energy storage function. According to different technical characteristics, energy storage elements can be divided into high-energy type and high-power type. Generally speaking, there is a difference between high-power batteries and high-energy batteries, and supercapacitors are basically used as high-power energy storage elements.
1, fuel cell vehicle power control system
A power control system of a fuel cell vehicle comprises an energy subsystem and a motor drive subsystem, wherein electric energy is transmitted between the two subsystems through a DC bus; an energy manager, a fuel cell engine and a power storage battery are arranged in the energy subsystem, and the energy manager is respectively connected with a CAN communication controller in the fuel cell engine and the power storage battery; The motor drive subsystem consists of a vehicle manager and a drive motor with a motor controller, and the vehicle manager is connected with the motor controller. The pow control system of that fuel cell vehicle of the invention adopts a modular design, can reasonably configure and use all its component and give full play to the performance of its components, and is a general optimized power control system structure.