Hybrid Synergy Drive

Hybrid Synergy Drive ( HSD abbr. ) is a brand name for the hybrid drive system from Toyota. He is currently in the Toyota Prius, Toyota Auris, Toyota Auris Touring Sports, Toyota Yaris, Toyota Prius , offered Toyota Prius Plug-in Hybrid, and various Lexus models. In America and Japan, he is also offered in other Toyota models as well as licensed to Nissan and Ford.

The HSD is a fuel-efficient propulsion system for vehicles and has received numerous awards for this. Passenger car with hybrid drive ( of which the Hybrid Synergy Drive represents a part ) are far more popular in Europe than in the USA. In the year 2010 291.000 hybrid vehicles were sold in the U.S., in Europe, however, only 110,000. In Japan, cars are common with hybrid drive most. So there 492,000 units were sold in the same year.

5.1 Driving the HSD
5.2 Operation modes of the HSD

6.1 advantages
6.2 disadvantages
6.3 Special features / characteristics

Versions

The first in hybrid powertrain vehicle (Toyota Prius 1997) drive system used was known as the Toyota Hybrid System ( THS ). In 2003, the second generation Prius ( NHW20 ) came with the improved THS- II on the market. This system appears under the brand 's Hybrid Synergy Drive ( HSD short ). The Hybrid Synergy Drive is the drive assembly of the Toyota Prius model year 2003 ( as of May 2006). A more powerful version of THS -C is used in the hybrid vehicles of the Lexus brand. This system marketed by the manufacturer under the name of Lexus Hybrid Drive. In published in 2009, the third version of the Toyota Prius again evolved HSD has been introduced. The published at Toyota 2010 Toyota Auris HSD and has been available since 2011 Lexus CT 200h use an identical system as the Prius 3

Use

The first passenger car that was equipped with the HSD, was the Toyota Prius. Toyota builds but it is now also in other automobiles. These are: Toyota Alphard, Toyota Auris, Toyota Auris Sports Touring, Toyota Camry, Toyota Highlander, Toyota Previa, Toyota Prius Plug -in Hybrid, Toyota Prius and Toyota Yaris.

When Toyota subsidiary Lexus of HSD, the Lexus Hybrid Drive means there is offered in the following models: Lexus CT, Lexus IS, Lexus GS, Lexus HS 250h, Lexus LS 600h, and Lexus RX.

Construction

HSD is a unit of a combustion engine and two motor generators, and a high battery capacity, and an electronic control unit. HSD is a power-split hybrid drive, in which by means of power split device, the power of the internal combustion engine and the electric motor is distributed. The structure of the HSD is described using the example of the Toyota Prius the third generation.

Power Split Device

The power split device consists of a planetary gear unit and an electronic controller. It determines the gear ratio between the engine and the output shaft. It also adjust the power flow depending on the control of motor generators possible. A clutch, there is not, in any operating state, all the components are positively connected to each other.

The internal combustion engine

In all until today (2011) on the market of vehicles with HSD a 4 - stroke petrol engine with camshaft adjustment is used. Since the second-generation Prius that is operated in the Atkinson cycle. It has 4 cylinders, 1.8 liters and 73 kW (Toyota Prius & Auris, Lexus CT 200h ).

Motor generators

The two electrical units of the HSD is referred to by Toyota Motor generator, since they can act both as a generator and as a motor. They are abbreviated as MG1 and MG2. The electro- technically correct term for this type of motor is three-phase synchronous machine with permanent magnet excitation.

The less powerful MG1 (42 kW during model generation 3) is generally used together with the MG2 to start the engine and while driving a generator. By changing its rotational speed and the gear ratio is deviated is set with which the internal combustion engine delivers its output to the ring gear and thus the drive wheels.

The stronger MG2 serves as a direct drive motor and a regenerative braking for recovering the braking energy. In the Prius the third generation, he has a power of 60 kW.

Batteries

An important element of the HSD is the high-performance battery pack. This is considerably more powerful than the starter battery used in conventional cars. It is a nickel -metal hydride battery, while starter batteries are almost exclusively lead-acid batteries. In available from 2012 Prius PHV, a lithium -ion battery with 4.4 kWh is used (used net loading window approximately 3.0 kWh). The Toyota Prius is a smaller Li- Ion battery is used.

The voltage of the Ni -MH battery pack is 201.6 volts. It has a maximum power output of 27 kW (third generation ), which is also the maximum available power for the electric motors, with the internal combustion engine can be supported. For comparison, the voltage of a conventional car starter battery is 12 volts, its maximum power about 2 kW.

The high-performance battery of the HSD was designed for a high cycle stability. Because he never fully charged and discharged beyond ( from 40% to 60 % usually in downhill recuperation up to max. 80%), its lifetime is as high as that of the vehicle itself, the analysis of data from 36,000 Toyota Prius revealed that these vehicles - and thus the batteries - had an extremely high reliability. In an experiment conducted in the United States test the performance of a new Toyota Prius was compared with that of a vehicle that had a mileage of 300,000 km after ten years. Acceleration and consumption were almost unchanged, which suggests that even the power of the battery had hardly subsided.

In addition to this battery pack every car with HSD also has a conventional, significantly smaller 12 -volt battery. Should fail in case of failure of the high voltage circuit, together with high performance Ni -MH battery while driving, it is therefore ensured that the on-board electronics, which is across manufacturers consistently operated at 12 volts DC, further work. Since this battery is not intended to start the engine, it has a lower capacity than conventional starter batteries.

The Boost Converter

The existing since the second-generation Prius boost converter increases the voltage of the Ni -MH batteries in the amount of 201.6 volts to a maximum DC voltage of up to 650 volts ( 3 Prius, Prius up to 500V 2 ), which - after transformation in three - phase motor generators are fed. If MG1 and / or MG2 operate as a generator, it converts the rotational flow around ( during model generation up to 500V 2 ) into the DC charging voltage of just over 200 volts in the amount of up to 650 volts.

Inverter

With the aid of an inverter 650 -V DC voltage is converted into a variable-frequency three-phase current, the motor generators are supplied. Two electric motors, of the boost converter and the inverter, are water- cooled by means of an independent circuit from the engine. A second inverter converts the output from the hybrid battery DC voltage in the amount of 201.6 volts into a three - phase alternating voltage of the same height in order to power the air conditioning. This inverter is integrated since the model generation 3 in the case of E-Antriebs/Klimakompressors.

HSD in a number of sensors are active. The most important are: position and speed sensors for MG1 and MG2, with which not only the current speed, but also the exact angular position of both motors can be determined. By measuring the current balance on the respective motor generator acting force is in addition also known exactly.

Other sensors record the position of the accelerator and brake pedal and move the shift lever.

Control electronics

HV ECU (High Voltage Electronic Control Unit): It controls the flow of energy between the battery and the two motor generators. The HV ECU monitors next to the safe operation of the hybrid drive and stores operating data for easier troubleshooting. In case of failure it can take the high-voltage circuit with the help of three relay out of service.
Skid Control ECU: It controls and monitors the regenerative braking.
Battery ECU: You monitor the charging status of the battery pack and controls the cooling.

Stages of development

Since its introduction in 1997, learned the HSD numerous improvements. So had the engine of the Toyota Prius I just 1.5 liter displacement and 43 kW power, whereas after area of 2009 presented ZVW30 Prius has an internal combustion engine with 1.8 liter displacement and 73 kW. The largest internal combustion engine, which today is used in a HSD, is a V8 engine with 5 -liter displacement and 290 kW in the Lexus LS 600h. Parallel to the power of the engine increased the power of the electric motors, and thus the overall system performance.

The two motor generators have been operated in the first Prius generation of a voltage identical to the voltage of the battery pack of 274 volts. The first Prius model, there were sometimes problems due to overheating of the power electronics. Therefore, this was water cooled from the second generation. With the introduction of the second generation Prius the battery voltage was lowered to 201.6 volts, but increases the motor generators using the to -down boost converter to 500 volts. When Prius III of this boost converter operates at a peak voltage of 650 volts.

Due to the direct connection at the first and second generation Prius the rotational speed of MG 1 was identical to the speed of the sun gear and the rotational speed of MG 2 are identical with the revolving speed of the ring gear. HSD the third generation ( for example, used in Prius ZVW30 2009 ) has on the contrary a further planetary gearing, which halves the number of revolutions of the ring gear with respect to about MG2. Thus, the rotational speed of the sun gear and thus the speed of MG 1 halved When the Prius first and second generation, the permitted maximum speed of MG 1 limited the maximum speed could be driven in pure electric mode with the. The additional reduction with the help of the second planetary gear unit can be electrically driven at much higher speeds with this extended HSD now, which is particularly important in the Prius PHV, which has significantly more powerful battery. Also in the THS -C, a further development of the company Lexus, an additional gear is used.

Since the internal combustion engine of a passenger car with HSD is operated at a very high efficiency, and decreases little heat, can be heated with the engine, the catalyst and the vehicle interior. This problem was encountered in the HSD of the third generation, as it comes in Prius ZVW for use with a heat recovery system. The heat recovery system in the Toyota Prius , which will be introduced in 2012, further improved. This vehicle comes under the name of "pitch and bounce control" a newly developed control system is used, which will reduce bounce of the vehicle in the form of pitching with bad roads by counteracting control the drive.

Function

The Hybrid Synergy Drive is easy for the driver to operate; to ensure this, and to ensure optimum operation condition, a number of control loops are constantly active.

Driving with the HSD

A pressure on the accelerator pedal in the state causing (usually) that is accelerated by the electric motor MG2; when a certain speed of the internal combustion engine is started automatically and smoothly. He can now contribute to the acceleration, these take over completely or both accelerate and load simultaneously with the help of the now acting as a generator, electric motors, the batteries. Conversely, in a braking operation at the required low braking power be braked with the generators and fed into the energy of the batteries. Only if the required braking power is higher than what the batteries can absorb, even the conventional brakes are involved in the braking process. All of this happens automatically and unalterable for the driver.

The operating modes of the HSD

On the speed of the sun gear, that is, the motor generator MG 1, the translation and thus set the rotating speed of the internal combustion engine. The internal combustion engine can be operated over a wide speed range from standstill to maximum speed. However, the maximum speed of MG 1 limited in the models before the Prius III the controllable range; the internal combustion engine may not rotate at the rotational speed at its maximum power THS and THS- II at a low speed; Therefore, for a quick start performance of the engine and the large motor generator MG 2 is used together. At very high speeds the engine can not be stopped, because in this case the maximum speed of MG1 (or both electric motors in the Prius III) would also be exceeded. The internal combustion engine and one of the two motor generators serve both the propulsion of the vehicle and can perform this task each exercise alone or in combination. Motor generator MG 1 serves primarily as a generator and starter. The hybrid vehicle can take so the following operating states:

Pros and cons of the concept

An internal combustion engine can not be operated at a speed close to 0. For starting a mechanical coupling is in cars with manual transmission therefore necessary. For automatic transmissions, at standstill ( in gear position D) and very low speeds of the car is headed accumulating power in the hydraulic converter. In both cases, engine output power is converted into heat and is thus no longer available. In contrast to the internal combustion engine, an electric motor of a rotational speed of 0 to be operated at low speed and provides a high torque - rotational speed even when the hybrid 0 Synergy drive an electric motor is used for starting. In contrast to this there are no mechanical coupling such friction losses. This kind of startup is wear-free and low losses.

A spark-ignition engine has at low speeds, a lower power. In order anytime a power reserve to have available in the car, is therefore rarely driven with the optimal consuming aspects low engine speed. Rather, the driver selects a lower gear and thus a higher speed than for the recalled power is actually needed. So that the internal combustion engine is operated with a relatively low load. The efficiency of a gasoline engine, however, is considerably reduced at low loads, which is caused inter alia by the throttle loss.

In a conventionally powered car, the driver (or the automatic transmission ) can indeed drive by driving or accelerating in high gear with high load and high efficiency; but demanded more power, it can be achieved only by a speed increase, ie, by choosing a smaller gear. Shift and change in speed of the engine need this time. In practice, therefore, hardly a driver drives at low speeds in the high gear.

At very low speeds up to 50 km / h to hold the speed is so little power is needed, that the internal combustion engine of a mid-size car by lowering the engine speed can not be operated in the vicinity of its optimum efficiency. When the value falls below about 1200 rpm, the efficiency of a passenger car gasoline engine drops back and can namely by running under load at low speeds below 1,000 rpm even be damaged. To hold a speed of 50 km / h, a power of about 5 kW is needed. In the normal in city traffic speed range, it is under power saving aspects, is therefore sensible to run a car with stored energy in battery electric.

Since the energy density batteries available today is far less than that of gasoline or diesel, despite significantly higher efficiency of the electric motor, the battery of a pure electric vehicle in intercity and highway driving are disproportionately quickly emptied or disproportionately large, heavy and expensive. Purely electric vehicles with high ranges for intercity and highway driving currently are therefore the exception.

Benefits

The Hybrid Synergy Drive allows you to regulate speed and power of the engine regardless of the required drive power. The internal combustion engine is used, it can thus be operated at a constant and high load with high efficiency. Fast power request can be served directly when the Hybrid Synergy drive motor generator MG2, while this means of motor generator MG 1, the ratio is changed in parallel, so as to increase the speed and power of the engine. Consequently, the internal combustion engine without sacrificing comfort can always be operated with high efficiency.

Other advantages are:

The engine has no unnecessary idling; with the exception of the warm-up phase, the combustion engine is only started if it can be operated with high efficiency; at low speeds, or when no or only a low driving power is needed, the internal combustion engine stops. This happens not only when stopping at a red light, but even when going downhill when the driver releases the accelerator pedal fully or example, in a 30 kph zone.

The HSD enables over the entire speed range, seamless acceleration. Start and stop of the engine is always done smoothly and without interruption of traction.

Since a large portion accruing brake energy is used to charge the batteries ( = recuperation), brake wear is much lower and the consumption of ascent and descent in general is greatly reduced. While braking energy can also be reused in conventionally -powered car; However, the greatly powerful rechargeable batteries, the Hybrid Synergy Drive allow a much higher charging current and thus to use a greater braking power for recuperation, as with conventional starter batteries is possible due to their high capacity.

The efficiency of the HSD is approximately 45% compared to 40% of a diesel engine and 35% of a conventional gasoline engine.

During the service life of the engine of the car is extremely quiet to noise, resulting in a relaxed driving contributes (red light, traffic jam, downhill ). This is also useful if the car is to be moved in noise- sensitive environments.

When the engine to the interior heating or for the rapid heating of the catalyst (to minimize the emission of pollutants ) is warming up, it charges the battery.

The HSD drives like a car with automatic transmission. The driver selects only if he wants to go forward or backward.

The steadily increasing in recent years, the number of electrical consumers burdened the electrical system of today car much more than was previously the case, what batteries and alternators must be dimensioned accordingly (examples: start-stop system, heater, seat heating, rear window heating, lighting, car radio, etc.); Increase the alternator and the battery, the vehicle weight, but are not needed for driving. In the Hybrid Synergy Drive very powerful batteries and generators are carried on principle, which are used not only in the state but also while driving.

With the necessary for the hybrid drive, powerful accumulators units can be powered off when the internal combustion engine, which would overload the existing battery capacity in conventional cars (eg air conditioning).

The electrical operation of ancillary units, which are driven in conventional passenger car from the engine, allowing more efficient operation (air conditioning, power steering, water pump for engine cooling, brake booster ).

Since the engine cooling system is operated fully electrically, the engine can be safely switched off immediately after a prolonged full load requirement without causing heat to build up in the engine block, because the cooling water pump can continue to run even at standstill of the engine.

A great advantage of this hybrid concept is the avoidance of partial load runs in which conventional petrol engines can be operated with very low efficiency. Diesel engines operate at partial load operation, however, significantly more efficient than gasoline engines - compared to diesel engines of HSD therefore not benefited terms of part load runs at the same rate .. Therefore, the reduction in fuel consumption through a combination of diesel engine and HSD rather limited.

As a motor, which operates in the Atkinson cycle, produces less heat, the engine cooling system can be made smaller. This not only reduces cost, space and weight, but also reduces the air resistance by a smaller radiator surface, and it shortened due to the lower amount of coolant warms up the engine. This reduces the emission of pollutants, which is the highest in all gasoline engines in the warm-up phase.

Disadvantages

The accompanying batteries increase weight and reduce potentially the amount of available trunk. As is housed in Auris and Yaris II of the hybrid battery under the rear seat there is still no boot limitations over the non hybrid variants. Overall, you can see the Yaris and Auris that the hybrid version is slightly heavier than pure gasoline, but still lighter than the respective diesel models.

Since the internal combustion engine is operated with high efficiency, little heat is charged to the interior heating. This is more than offset by an exhaust heat recirculation on the Prius, the third generation.

The maximum total system performance of the Prius III (100 kW) is available only for a few seconds to max. 3 Minutes on the piece available. Namely only until the battery is empty. Thereafter the car is only the power of the engine (73 kW). Only after a drive of less than 73kW is available again for a further short period the full system power. This disadvantage is during long trips at full throttle on the mountain and in particular noticeable even at full throttle when towing a trailer. However, when overtaking or generally brief acceleration, it is not noticeable, because then and before that the battery is charging on both occasions. [Note 1]

Special features / characteristics

Increase the hybrid components is not necessarily the weight of the vehicle, because the extra weight is partially offset by the elimination of some components such as clutch, alternator, starter, complex manual transmission with additional electric motors and batteries.

The maximum at full load the entire system in addition to the internal combustion engine can be output by the electric motor power is the maximum power output of 27 kW of the battery (3rd generation ) is limited by the maximum allowable current, ie. This is lower than the maximum power of the electric motors. If the engine is not operated in full load, it can generate additional electricity through the generator, which is used again in the second electric motor. In this case, the electric motor may well deliver more than 27kW ( from the battery ) to the wheels, eg when reversing.

Switching off the internal combustion engine during the drive is only possible up to a certain speed; is the internal combustion engine, the rotational speed of the electric motor is higher, the faster the vehicle is traveling. The permissible maximum speed of the electric motors is limited so that the maximum speed at which the engine can be switched off. At Prius models of first and second generation MG 1 had limiting, since its speed was significantly higher than that of Mg 2. In the 3rd generation Prius, an additional reduction gear is installed, so MG1 and MG2 run almost identical speeds.

Since all necessary for driving systems ( power steering, oil pump, power brakes, air conditioning ) must be available even at standstill of the engine, they also need to work regardless. Therefore, they are driven electrically.

Synergy of the hybrid drive, inter alia, by lowering the recovery of kinetic energy into electrical energy during braking of the vehicle fuel consumption. For a substantially constant speed, eg when motorway driving, HSD has a lower fuel consumption advantage. It saves you by the variable translation and operated in the Atkinson -cycle engine will still remain on the existing highway, as this engine has the highest efficiency of all petrol engines.

Trivia

The Prius has been used as a generator to supply the domestic electrical system (power failure due to a storm ). This could be taken a maximum of 1000W via a voltage transformer connected to the 12V power supply. Once the drive battery was empty, jumped on the internal combustion engine to the recharge. In this way, 1 kWh of electricity could be generated from a liter of petrol consumption, which is quite competitive to the generation of electricity by means of a small petrol- electric generator. It is advantageous in that no unnecessary idling consumption arises and exhaust gases are cleaned over the catalyst.

Lexus LS (XF40) Nissan Motor Company Nissan Altima Ford Escape Hybrid Block heater Head unit Energy-efficient driving

404640