## Volkswagen Group’s MQB plug-in hybrid powertrain; foundation for Golf GTE, A3 e-tron, and more

##### 03 April 2014
 The MQB plug-in hybrid powertrain serves both the A3 e-tron and the Golf GTE. Source: Volkswagen AG. Click to enlarge.

The first two mainstream plug-in hybrid electric vehicles from the Volkswagen Group—e.g., not the $845,000 base price plug-in hybrid Porsche 918, earlier post, or even the$100,000 Porsche Panamera S E-Hybrid, earlier post—the Golf GTE (earlier post) and the A3 e-tron (earlier post), are both based on the same MQB (Modularen Querbaukasten, or modular transverse toolkit) plug-in hybrid powertrain.

The Volkswagen Group’s MQB modular toolkit is one of the four main modular toolkits (modularen Baukästen) of the Group: the MQB (transverse); the MLB (longitudinal); the MSB (standard drive); and the NSF (New Small Family). The toolkits standardize many vehicle component parameters across brands and vehicle classes, while at the same time offering access to new technologies, such as alternative drive systems. The new Mark 7 Golf, which is MQB-based, offers gasoline; diesel; natural gas; plug-in hybrid (the GTE); and battery-electric (the e-Golf) versions, all of which can be manufactured bumper-to-bumper on the same assembly line. The MQB spans the A0 to C segments.

 The MQB strategy of the Volkswagen Group extends from the A0 to the C-segment. There is some overlap at the low-end with the NSF and in larger vehicles with the MLB. Click to enlarge.

The modular toolkit approach, in this case the MQB, also offers flexibility. For example, the CrossBlue Coupé plug-in hybrid sporty mid-size SUV show car, introduced at Auto Shanghai 2013, is also based off the MQB architecture, but featured a transverse-mounted turbocharged direct-injection (TSI) 220 kW (295 hp) 3.0L V6 gasoline engine (EA 390) and six-speed DSG dual-clutch automatic transmission with 40 kW electric motor as part of the DQ400E hybrid module in the engine compartment, rather than the 1.4-liter engine and 80 kW motor DQ400E in the A3 e-tron and Golf GTE plug-in hybrids. (Earlier post.)

 Example of an MQB plug-in hybrid powertrain. While the electric motor and battery pack are the same size as spec’d for the A3 e-tron and the Golf GTE, the combustion engine (VB) is at a lower power rating. Click to enlarge.

The Volkswagen Group has said the Audi A3 e-tron will come to the North American market in 2015; introduction plans and timing for the Golf GTE are as yet unspecified. However, given their lineage (the A3 and Golf), the vehicles will be key components of the Group’s broader—and aggressive—electrification strategy, enabled and accelerated by the MQB and its cousins.

As one example, an MQB-based Passat plug-in hybrid will join the line-up “soon,” according to Volkswagen Group Chairman of the Board of Management Prof. Dr. Winterkorn in remarks prior to the Geneva Motor Show in March. (Earlier post.)

 From a 2013 Volkswagen Group presentation. Click to enlarge.

The Golf GTE and Audi A3 e-tron. The plug-in hybrid drivetrain is designed as a parallel hybrid system. The basic main components common to both the Golf GTE and the A3 e-tron are:

• a 4-cylinder, 1.4-liter TSI gasoline engine from the EA 211 series (which spans 1.0L to 1.6L displacement);

• the DQ400E dual-clutch gearbox (combining the electric motor, engine-disconnect clutch and base gearbox into a highly integrated, compact unit);

• the 80 kW liquid-cooled electric motor (HEM80), integrated into the DQ400E; and

• a liquid-cooled 8.8 kWh Li-ion battery pack (about ~7.0 kWh usable).

The brake system uses an electromechanical brake booster (eBKV, elektromechanische Bremskraftverstärker). It divides the required deceleration power according to demand between the electrical and hydraulic systems, and enables a high degree of recuperation. (The system is also being developed for application in non-hybrid applications.)

All-electric range is projected to be up to 50 km (31 miles); on a 2/3 all-electric and 1/3 hybrid route, the Audi and Golf are expected to deliver an average NEDC fuel consumption of 1.5 l/100 km (157 mpg US), or 35 g/km of CO2.

DQ400E. The DQ400E will be the Group’s main near-term gearbox for all hybrid and plug-in hybrid applications that are transverse, noted Oliver Schmidt, General Manager Engineering and Environmental Office, Volkswagen Group of America, at the SAE 2013 Hybrid & Electric Vehicle Technologies Symposium. (Earlier post.)

The friction-optimized unit, with six forward gears, features oil supply on demand, two-circuit hydraulic control (high and low pressure, 40 bar and 5 bar) and a highly efficient synchronizer system. The power flux is divided across two component gearboxes using a coaxially split drive shaft with an upstream drive clutch for each. The wheel set is of a highly compact design to make space for the electric motor.

The DQ400E system is equipped with two drive clutches (K1/K2) and the engine-disconnect clutch (K0). The drive clutches are each designed for maximum input torques of 400 N·m (295 lb-ft); the engine-disconnect clutch for 350 N·m (258 lb-ft).

The engine-disconnect clutch actuation unit is installed in the clutch chamber between the rotor arm of the electric motor and the input shaft; the rotor arm is a component element of the electric motor and of the drive clutches.

 HEM80 motor. Click to enlarge. The DQ400E transmission. Click to enlarge.

HEM80 electric motor. The 80 kW, 330 N·m (243 lb-ft) three-phase permanently excited synchronous machine is located in the hybrid module on the input shaft, between the engine-disconnect clutch and the drive clutches (K1/K2). It is integrated into the vehicle’s on-board cooling system.

The rotor and stator are made of punched electric sheet steel. The rotor integrates the permanent magnets, while the stator incorporates the three-phase copper windings. Sensors detect the rotor position, providing an input variable for control of the phase currents through the power electronics.

Li-ion battery. The Li-ion battery pack comprises eight modules, each made up of 12 prismatic nickel-manganese-cobalt cells. The Battery Junction Box (BJB) and the Battery Management Controller (BMC) are integrated into the die-cast aluminium and plastic battery casing. Voltage is between 250 and 400 V depending on state of charge.

Thermal management. The plug-in hybrid uses a three-circuit cooling system: one high-temperature circuit and two low-temperature circuits.

The high-temperature circuit handles the engine; the integrated gearbox oil cooler can be shut off on the water side, enabling the gearbox to be both heated and cooled. In electric driving mode the interior is heated by the high-voltage auxiliary heater (PTC). Heat sinks (cold gearbox, cold combustion engine) can be disabled in EV mode by means of bypass lines to provide rapid system response and high levels of air-conditioning comfort.

Low-temperature (LT) circuit 1 conditions components with an average operating temperature of 75 to 90 °C, such as the charge air cooler of the engine and the electric motor. LT circuit 2 handles power electronics, charger and high-voltage battery; these three components can be cooled according to demand, both passively by the LT cooler and actively via the air-conditioning circuit, which is connected to the LT circuit 2 via a chiller. LT circuit 2 can additionally be divided into two sub-circuits, enabling different temperature requirements of the various components to be met.

Drive management and operating modes. The hybrid operating strategy and drive management functions are also incorporated within the MQB. Aspects of this include:

• An engine restart request is determined by the operating strategy in the engine control unit and transmitted to the gearbox control unit. During the start sequence, the DQ400E coordinates the torques of the electric motor and the combustion engine, with the corresponding slip control of the wheel torque-dictating dual clutch (K1/K2).

The receiving torque of the engine-disconnect clutch (K0) is balanced by a compensation torque of the electric motor so that the wheel torque remains constant. After fuel injection and ignition is enabled, the engine-disconnect clutch is re-opened; the combustion engine runs virtually load-free. Its speed is balanced to that of the electric motor by way of a torque request.

Once the two components are synchronized, the engine-disconnect clutch is closed. After starting, the torque coordination is returned to the engine control unit.

• The catalytic converter is heated with the engine-disconnect clutch opened, and therefore independently of the driving profile. In the process, the combustion engine is run under no load at any adjustable speed level; torque is provided by the electric motor.

• Plug-in hybrid systems can run for very long periods without the combustion engine being active. Long off-times necessitate intermittent refilling of the engine oil gallery. For this, the engine is briefly turned over in order to provide a component-protecting minimum lubrication.

• The plug-in operating modes include EV mode; hybrid hold mode; hybrid automatic mode; hybrid charge mode; and sport mode.

In EV mode, maximum speed is 130 km/h (81 mph).

In hybrid hold mode, the state of charge of the high-voltage battery is held at a constant average value (charge sustaining). The vehicle behaves like a full hybrid, utilizing approximately 1/8 of the capacity of the high-voltage battery for maximum efficiency.

Hybrid automatic mode is based, among others factors, on predictive route data, in order to optimize the consumption of electric power until the next charging station. This mode also provides for moderate recharging.

In hybrid charge mode, the high-voltage battery is charged during driving by the combustion engine.

In sport mode, full drive performance is available with the combustion engine and the electric motor. By continuously recharging to an increased average SOC, the operating strategy guarantees maximum boost performance in this mode. A slightly increased thrust torque enhances sporty performance.

Resources

• Hanno Jelden, Kai Philipp, Norbert Weiss, Andreas Kessler (2014) “Der Plug-In Hybrid Des Modularen Querbaukastens Von Volkswagen,” MTZ - Motortechnische Zeitschrift Volume 75, Issue 4, pp 40-47 doi: 10.1007/s35146-014-0315-7

An interesting design decision VW have made is to use liquid battery cooling for their plug ins, but stick to passive air cooling for their BEVs

Hybrids are the SUV's of 2010's
They make a killing off of them.
They get the greenies who dont drive more than the Electric range
and still get all of the ongoing costs of an normal gas car

If Tesla can produce a car with a range for 40k
that could be a game change that would put alot of dealerships out of business. Which wont happen because to many politician will block Tesla in there state

What happens in Vegas can drive to any state. If Tesla can bring down the price, politics won't stop, just slow it. At some point the market does work.

To my point, Texans buy the second highest number of Teslas in the US, but Tesla is not able to sell them there. That is one reason Tesla is considering locating their mega battery factory in Texas -- politions can be bought by either side of the issue.

There are no legal limits on the purchase price of politicians in USA. Some have sold out for $38.6 million recently and prices are going up fast. We will see$100+ million soon. That's one of the way to move to the 1% group.

Very interesting and ingenious,... but that should not hide the fact that current German sizing for Batteries in latests PHEVs is "wrong", across all power trains presented above, and across all other beloved German brands too. I mean their "common" <10KWH standard is just "wrong". For my daily commutes of 60KM # 40M, to do them "all Electric" as I dream to in Paris where Ecologists just re-elected in townhall will soon prevent non-EV SUVs to access, with <10KWH I would need to secure 2 x full charges per day at least. Means one at home during the night, and one at my company car park during the day, with all plug-in equipment required and always available when I park on each side. At home it should be easy to set as I have a private dedicated parking slot, in the private car park underneath my flat building. But for my work they have set nothing yet, and if they set anything, it will only be a few slots equipped, and used first-come first-served like for everything else, so no way for me to count on that every day. Hence why I need a minimum of 25-30KWH of battery to jump into this promising PHEV "car of the future" train, so I can go with only 1 x charge per 24H at home during the night, plus have a range extender so I can also go on vacation with that same sole car of my familly (Forget 2 x cars in big cities like mine). I have to replace by beloved old BMW 530DA within a year, and still found ZERO PHEV I could buy in that time frame at my €60K = $80K mid-range SUV budget. Closest is the Volt but form factor not for me. I'm on an BMW X4/X5 SUV or Audi Q5, forgetting the marvellous Porsche Macan that cost too much, unfortunatly... The 1st one that comes out with one properly serviced in Europe I buy it! Davemart and Patrick, you can ignore this post. Your commentaries about VW design choices (both very prescient, BTW) don't address the real, elephant-in-the-room topic that pervades GCC. I think we all know what that is: America is trying to kill EVs. I agree that it's obvious how hard the US is working to stop the global wave of mobility electrification. The evidence is everywhere. The US share of the auto market for the past four years has ranged from 16-19% of global production. Yet the US purchased over 40% of Prius produced, and nearly half of PHEVs. It should be obvious that Dark Forces in America are buying these cars to keep them off of world markets lest there be a rush on them! That's clearly why the Advanced Technology Vehicle Manufacturing program led the world in funding at about USD8Billion to date, with a similar amount about to be released. Clearly, we are trying to corner the world's intellectual resources in this area to lock them away. Never mind that over USD1Billion went to a Japanese/French owned company. Oops... also never mind that the intellectual and physical assets of two failed ATVM projects, Fisker and A123, were sold to a Chinese company at discount of over 50% on US government funds with essentially no restrictions on their use. Obviously we're trying to keep this stuff out of the hands of global greenies. Also I don't think anyone can deny that the US is trying desperately to keep the Chinese from advancing in this field. Federally-funded research at US universities in cooperation with Chinese and other institutions around the world is a clever ruse, as is the fact that the majority of publicly-traded shares in BYD and KNDI are American-owned. Also the fact that there are no export restrictions on technical data developed in the USD125M JCSER battery project is another smokescreen. But the real outrages are US capital markets that have raised billions for everything from bio-fuels to battery technology to EV manufacturing. American entrepreneurs continue to risk megabucks on these ventures despite the fact that most CleanTech ventures have failed in the last few years. Why? Come on... it's obvious: we want to scare the rest of you off! And when one of them does sneak through, the US markets are quick to punish them. (Ignore the fact that TSLA has a market cap exceeding Fiat.) A site like Green Car Congress couldn't even exist in America and it surely wouldn't be founded by American... oops.... it does? They ARE? Well, it's time to tell you the truth, and solve this problem once and for all. I am a Jewish Saudi Freemason Illuminati global banker oil baron (did I get all of them?). Yes, it's true. I have all the plans for 100mpg carburetors and "10-10-10" batteries locked in my safe. I fired the shot that killed JFK. If you look closely at the blurry photographic evidence you'll see me scurrying up the side of WTC7 with a satchel of explosives. And I'm paid by George Soros AND Charles Koch. God, that's a load off my mind. Maybe now that all this is in the open, we can focus on technical, regulatory, and market-driven discussion. I'll be watching the keystroke counters I've put into your devices to insure that you do... Thanks Herman More typing than I have time for but pretty much in line with my thinking. The VW vehicles look like a serious attempt to provide a range of electrified options along with other high efficiency vehicles. Two days late, Herman. Herman, Ponder this,$20 billion for Twitter, but battery and fuel cell companies beg for every dime. Rather odd that an entertainment/advertisement site would get more investors than companies doing good for human kind.

"politions can be bought by either side of the issue."

JMartin, I don't think Tesla is 'buying politicians' with their Gigafactory. There is a fundamental difference with 'campaign contributions' (aka legalised bribes).

First and foremost, the gigafactory does not profit the politicians directly and/or personally, rather it is for the state economy. The legislature has every right to amend laws to favour their economy. There is nothing insidious about that.

Arne, I would wager that the vast majority of influence peddlers/buyers are acting out of earnest belief in the righteousness of their cause. Ponder this venture fund's mission statement as an example:

"The Westly Group is dedicated to building companies that will solve the world’s most pressing problems. From next generation electric vehicles to healthy school meals, we invest in exceptional teams scaling transformative technologies and business models. We believe in the power of the passionate entrepreneur—whether sitting in a modern office tower or a Silicon Valley garage—to change the world."

So who is this saintly Westly group? It's a fund run by Steve Westly, who was a key early investor in Tesla, and a member of the BoD up through the IPO. Probably made a ton of dough when the offering was floated (and that's OK to me, BTW).

Oh, I forgot one thing: he was an important bundler of contributions (to the tune of hundreds of $k) to the Obama election campaign in 2008. Do you think this helped Tesla when they needed repeated restructuring of their DoE Loan (all paid back, I know, but only after 4-5 "adjustments" to payment terms and covenants)? Did it also help that Nick Pritzker, another significant Tesla investor, was coincidentally married to Penny Pritzker, the national finance chair of Obama’s 2008 campaign? I don't think there's a single poster to this site who thinks Tesla Motors is an evil enterprise. But not everyone in the world would agree based on the trail of political influence. We all pick the ones we like and rail against the ones we don't. It's all just business as usual. Addressing Patrick Free's remark about the small size of battery of the VW PHEV's, I need to remind everyone that the world's second largest automaker has the obligation to spread out battery capacity over as many cars as possible, in order to keep the price of Lithium to within affordable range. Please note that the world's largest automaker, Toyota, kept their PHEV to about 10-15 mile AER with only a 4 kWh battery. This is done to ensure future success of PHEV's into as many cars produced as possible. What I would like to see, though, is that beside performance models like VW are cranking out to satisfy the high-performance and Autobahn German market, perhaps VW will offer a more basic and affordable PHEV with only a 2-cylinder engine and no gear shift transmission, or only a 2-3 speed single clutch manual or automated manual, instead of a bigger and much more complex 6-speed Dual-clutch transmission, and with a much smaller fuel tank than that offered in the model in this article that can go for 550 miles...simply too big a fuel tank. 250-mile on a tank is enough, plus about 20-30 mile on electricity, would be plenty. At over 50 MPG, a 250-mile PHEV requires only a 5-gallon tank, which is much smaller and can be built stronger to reduce the risk of rupture and fire upon a major collision. VW stands for "folks' wagon" or "people's car," so, VW should stick to their tradition of the VW Beetle and offer a PHEV equally basic as the ultra-famous Beetle, the new PHEV having 2-cyl ICE of about 600-900 cc displacement, 6 kWh battery and perhaps a 60 kW motor with only a 3-speed single dry clutch manual transmission. With a small fuel tank of under 5 gallons, this vehicle should be competitive with a comparable ICEV w/ respect to internal space, price, and performance, while greatly excel over a comparable ICEV in term of fuel economy, reliability, and operating costs, with very little maintenance effort, about equal to a BEV. This new-generation of VW Beetle II PHEV, with a clean-sheet design optimized for the role of PHEV, will revolutionize the automotive world and will catapult VW into the top place as #1 automaker and the largest! Roger I was focusing on >€60K = >$80K high-mid-range cars / SUV segment. If Tesla can put 65KWH to 85KWH and still make a ton of profit on that segment, just missing the (small) Range Extender / electric generator so their users can also go on vacations with the same car today, then any German car maker could do a PHEV with 25KWH to 40KWH battery plus a range extender in the same budget and in their popular High End form factors, where volumes are small anyway. There is another reason why they don't do it. They are just protecting their High End Segment control-points (Huge ICE engines, Gear Boxes, and transmissions not required any more in full-Electric-Drive-trains PHEVs, and associated investments and factories, slowing down that PHEV transition as much as they could, as long as no serious competition threatens then on that segment, and they are only pushed to PHEVs by EU emissions standards that they accommodate only as much as needed.
Problem is not them, it's the other car manufacturers who failed on that HE segment before, and still have not understood that being 1st to come out with a PHEV built as a Tesla "all-electric-drive-train" with we much smaller 25-40KWH Battery pack, but with a Range Extender, could be a compelling reason for buyers to move away from the German brands, and them take over that HE segment. Why Renault/Nissan or even Peugeot in France are not pursuing that, especially when Renault/Nissan has all components and IP required for that, is a huge mystery for me. They may get subsidies from Petroleum Companies not to do this, and just keep playing with Full EV toys, that are only usable as second cars dedicated to local commutes, and priced 3X more than small ICE cars designed to do just that. No sure, but they are not stupid, nor blind, so bet there is a reason.

Thanks, Patrick, for the clarification.
I'm afraid that Tesla has already claimed significant market share of high-end luxury autos from \$75,000 to 100,000 range. You see, 180-300-mi range is very adequate for local driving, including to nearby cities, with topping off if needed here and there from SuperCharger stations. Rich folks don't do much long-distance driving because they'd rather fly and save time.

So, PHEV's are more favorable to middle-class folks who have to drive long distances out of necessity, and who have needs to carry a lot of luggage or haul a lot of people and so needing large cargo-passenger capacity for the long-distance drive, including pillows and blankets, beer coolers, foods, etc. A large battery capacity would simply add weight, cost, and would take away valuable internal space that middle-class folks really need!

Roger, you are right, Tesla already grabbed a part of that High End market, basically the smaller countries from where people fly more than driving away with their HE car, or in very wide areas like the US where people mainly drive near bye only, then fly and rent for more far away destinations. My bet is Tesla will struggle a lot more in the larger European countries like Germany, France and UK, or even Italy and Spain for ex. Where High End car owners love to take their family in the summer, in a very comfortable and reliable statutory car, to the Mediterranean sea in south of France, or Spain or Italy, and skying in the Alps in the winter... Buying an High end car that can't perform these critical tasks w/o risks, in August when millions of people rush to the same places and queues are endless, will be a challenge, dramatically limiting their market share here. It's just not thinkable for me without a range extender, even when Tesla will offer 160KWH battery, and some extended Fast charging network... w/o a Range Extender I won't buy. Can't take any risk on family vacations, sorry.

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