Solar and wind power curtailments are rising in California

Scotland Green Recovery Strategy centers on renewable energy, onshore wind, energy efficiency, battery storage, hydrogen, and electric vehicles, alongside public transport and digital infrastructure, local manufacturing, and grid flexibility to decarbonize industry and communities.

Key Points

A plan to cut emissions by scaling renewables, efficiency, storage, and infrastructure for resilient, low-carbon growth.

✅ Prioritize energy efficiency retrofits in homes and workplaces

✅ Invest in battery storage, hydrogen, and EV charging networks

✅ Support local manufacturing and circular economy supply chains

THE “green recovery” joins the growing list of Covid-era political maxims, while green energy investment could drive recovery, suggesting a bright and environmentally sustainable post-pandemic future lies ahead.

The Prime Minister once again alluded to it recently when he expressed his ambition to see the UK become the “world leader in clean wind energy”. In his typically bombastic style, Boris Johnson declared that everything from our kettles to electric vehicles, with offshore wind energy central to that vision, will be powered by “breezes that blow around these islands” by the next decade.

These comments create a misleading impression about how we can achieve a green recovery, particularly as Covid-19 hit renewables and exposed systemic challenges. While wind turbines have a key role to play, they are just one part of a comprehensive solution requiring a far more in-depth focus on how and why we use energy. We must concentrate our efforts and resources on reducing our overall consumption and increasing energy capture.

This includes making significant energy efficiency improvements to the buildings where we live and work and grasping the lessons of lockdown, including proposals for a fossil fuel lockdown to accelerate climate action, to ensure we operate in a more effective and less environmentally-damaging fashion. Do we really want to return to a world where people commute daily half way across the country for work or fly to New York for a two-hour meeting?

Businesses will need to adapt to new ways of operating outwith the traditional nine-to-five working week to reduce congestion and pollution levels. To make this possible requires Government investment in critical areas such as public transport and digital infrastructure, alongside more pylons to strengthen the grid, across all parts of Scotland to decentralise the economy and enable more people to live and work outside the main cities.

A Government-supported green recovery must rest on making it financially viable for businesses to manufacture here to reduce our reliance on imported goods. This includes processing recycleable materials here rather than shipping them abroad. It also means using locally generated energy to support local jobs and industry. We miss a trick if Scotland simply becomes a power generator for the rest of the UK.

MOVING transport from fossil fuels to renewable fuels will require a step-change that also requires support across all levels. The increased use of electric vehicles and hydrogen fuel cells are all encouraging developments, but these will rely on investment in infrastructure throughout the country if we’re to achieve significant benefits to our environment and our economy.

This brings us to the role of onshore wind power; still the cheapest form of renewable energy, and a sector marked by wind growth despite Covid-19 around the world today. Repowering existing sites with newer and more efficient turbines will certainly increase capacity rapidly, but we must also invest into development projects that will further enhance the capacity and efficiency of existing equipment. This includes improving on the current practice of the National Grid paying operators to switch off wind turbines when excess electricity is produced and instead developing new and innovative means to capture this energy. Government-primed investment into battery storage could help ensure we achieve and further reduce our reliance on traditional, non-sustainable sources.

We need a level playing field so that all forms of energy are judged on their lifetime cost in terms of emissions as well as construction and decommissioning costs to ensure fiscal incentives are applied on a fairer basis.

Turning the maxim of a green recovery into reality will require more than extra wind turbines, and the UK's wind lessons underscore the importance of policy and scale. We need a significant investment and commitment from business and government to limit existing emissions and ensure we capture and use energy more efficiently.

Andy Drane is projects partner and head of renewables at law firm Davidson Chalmers Stewart.

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AP Renewables Inc. Climate Bond Award recognizes Asia-Pacific project finance, with ADB and CNBC citing the first Climate Bond, geothermal refinancing in local currency, and CGIF-backed credit enhancement for emerging markets.

Key Points

An award for APRI's certified Climate Bond, highlighting ADB-backed financing and geothermal assets across Asia-Pacific.

✅ First Climate Bond for a single project in an emerging market

✅ ADB credit enhancement and CGIF risk participation

✅ Refinanced Tiwi and MakBan geothermal assets via local currency

The Asian Development Bank (ADB) and CNBC report having given the Best Project For Corporate Finance Transaction award to a the renewable energy arm of Aboitiz Power, AP Renewables Inc. (APRI), for its innovative and impactful solutions to key development challenges.

In March 2016, APRI issued a local currency bond equivalent to $225 million to refinance sponsor equity in Tiwi and MakBan. ADB said it provided a partial credit enhancement for the bond as well as a direct loan of $37.7 million, a model also seen in EIB long-term financing for Indian solar projects.

The bond issuance was the first Climate Bond—certified by the Climate Bond Initiative—in Asia and the Pacific and the first ever Climate Bond for a single project in an emerging market.

“The project reflects APRI’s commitment to renewable energy, as outlined in the IRENA report on decarbonising energy in the region,” ADB said in a statement posted on its website.

The project also received the 2016 Bond Deal of the Year by the Project Finance International magazine of Thomson Reuters, Asia Pacific Bond Deal of the Year from IJGlobal and the Best Renewable Deal of the Year by Alpha Southeast Asia, reflecting momentum alongside large-scale energy projects in New York reported elsewhere.

ADB’s credit enhancement was risk-participated by the Credit Guarantee Investment Facility (CGIF), a multilateral facility established by Asean + 3 governments and ADB to develop bond markets in the region.

APRI is a subsidiary of AboitizPower, one of Philippines’ biggest geothermal energy producers, and the IRENA study on the Philippines' electricity crisis provides broader context as it owns and operates the Tiwi and Makiling Banahaw (MakBan) geothermal facilities, the seventh and fourth largest geothermal power stations in the world, respectively.

“The awards exemplify the ever-growing importance of the private sector in implementing development work in the region,” ADB’s Private Sector Operations Department Director General Michael Barrow said.

“Our partners in the private sector provide unique solutions to development challenges — from financing to technical expertise — and today’s winners are perfect examples of that,” he added.

The awarding ceremony took place in Yokohama, Japan during an event co-hosted by CNBC and ADB at the 50th Annual Meeting of ADB’s Board of Governors.

The awards focus on highly developmental transactions and underline the important work ADB clients undertake in developing countries in Asia and the Pacific.

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Tesla Battery Day Innovations detail larger cylindrical EV cells with higher energy density, greater power, longer range, cobalt-free chemistry, automated manufacturing, battery recycling, and lower cost per kWh to enable an affordable electric car.

Key Points

Tesla Battery Day innovations are new EV cells and methods to cut costs, extend range, and scale production.

✅ Larger cylindrical cells: 5x energy, 6x power, 16% more range

✅ Automation and recycling to cut battery cost per kWh

✅ Near-zero cobalt chemistry, in-house cell factories worldwide

Elon Musk described a new generation of electric vehicle batteries that will be more powerful, longer lasting, and half as expensive as the company’s current cells at Tesla’s “Battery Day”.

Tesla’s new larger cylindrical cells will provide five times more energy, six times more power and 16% greater driving range, Musk said, adding that full production is about three years away.

“We do not have an affordable car. That’s something we will have in the future. But we’ve got to get the cost of batteries down,” Musk said.

To help reduce cost, Musk said Tesla planned to recycle battery cells at its Nevada “gigafactory,” while reducing cobalt – one of the most expensive battery materials – to virtually zero. It also plans to manufacture its own battery cells at several highly automated factories around the world.

The automaker plans to produce the new cells via a highly automated, continuous-motion assembly process, according to Drew Baglino, Tesla senior vice-president of powertrain and energy engineering, a contrast with GM and Ford battery strategies in the broader market today.

Speaking at the event, during which Musk outlined plans to cut costs and reiterated a huge future for Tesla's energy business during the presentation, the CEO acknowledged that Tesla does not have its new battery design and manufacturing process fully complete.

The automaker’s shares slipped as Musk forecast the change could take three years. Tesla has frequently missed production targets.

Tesla expects to eventually be able to build as many as 20m electric vehicles a year, aligning with within-a-decade EV adoption outlooks cited by analysts. This year, the entire auto industry expects to deliver 80m cars globally.

At the opening of the event, which drew over 270,000 online viewers, Musk walked on stage as about 240 shareholders – each sitting in a Tesla Model 3 in the company parking lot – honked their car horns in approval.

As automakers shift from horsepower to kilowatts to comply with stricter environmental regulations amid an age of electric cars that appears ahead of schedule, investors are looking for evidence that Tesla can increase its lead in electrification technology over legacy automakers who generate most of their sales and profits from combustion-engine vehicles.

While average electric vehicle prices have decreased in recent years thanks to changes in battery composition and evidence that they are better for the planet and household budgets, they are still more expensive than conventional cars, with the battery estimated to make up a quarter to a third of an electric vehicle’s cost.

Some researchers estimate that price parity, or the point at which electric vehicles are equal in value to internal combustion cars, is reached when battery packs cost $100 per kilowatt hour (kWh), a potential inflection point for mass adoption.

Tesla’s battery packs cost $156 per kWh in 2019, according to electric vehicle consulting firm Cairn Energy Research Advisors, with some studies noting that EVs save money over time for consumers, which would put the cost of a 90-kWh pack at around $14,000.

Tesla is also building its own cell manufacturing facility at its new factory in Germany in addition to the new plant in Fremont.

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Canada Green Investment Gap highlights lagging EV and clean energy funding as peers surge. With a green recovery budget pending, sustainable finance, green bonds, EV charging, hydrogen, and carbon capture are pivotal to decarbonization.

Key Points

Canada lags peers in EV and clean energy investment, urging faster budget and policy action to cut emissions.

✅ Per capita climate spend trails US and EU benchmarks

✅ EVs, hydrogen, charging need scaled funding now

✅ Strengthen sustainable finance, green bonds, disclosure

Canada is being outpaced on the international stage when it comes to green investments in electric vehicles and green energy solutions, environmental groups say.

The federal government has an opportunity to change course in about three weeks, when the Liberals table their first budget in over two years, the International Institute for Sustainable Development (IISD) argued in a new analysis endorsed by nine other climate action, ecology and conservation organizations.

“Canada’s international peers are ramping up commitments for green recovery, including significant investments from many European countries,” states the analysis, “Investing for Tomorrow, Today,” published March 29.

“To keep up with our global peers, sufficient investments and strengthened regulations, including EV sales regulations, must work in tandem to rapidly decarbonize all sectors of the Canadian economy.”

Deputy Prime Minister and Finance Minister Chrystia Freeland confirmed last week that the federal budget will be tabled April 19. The Liberals are expected to propose between $70 billion and $100 billion in fiscal stimulus to jolt the economy out of its pandemic doldrums.

The government teased a coming economic “green transformation” late last year when Freeland released the fall economic statement, promising to examine federal green bonds, border carbon adjustments and a sustainable finance market, with tweaks like tightening the climate-risk disclosure obligations of corporations.

The government has also proposed a wide range of green measures in its new climate plan released in December — which the think tank called the “most ambitious” in Canada’s history — including energy retrofit programs, boosting hydrogen and other alternative fuels, and rolling out carbon capture technology in a grid where 18% of electricity still came from fossil fuels in 2019.

But the possible “three-year stimulus package to jumpstart our recovery” mentioned in the fall economic statement came with the caveat that the COVID-19 virus would have to be “under control.” While vaccines are being administered, Canada is currently dealing with a rise of highly transmissible variants of the virus.

Freeland spoke with United States Vice-President Kamala Harris on March 25, highlighting potential Canada-U.S. collaboration on EVs alongside the “need to support entrepreneurs, small businesses, young people, low-wage and racialized workers, the care economy, and women” in the context of an economic recovery.

Biden is contemplating a climate recovery plan that could exceed US$2 trillion as Canada looks to capitalize on the U.S. auto pivot to EVs to spur domestic industry. Per capita, that is over 8 times what Canada has announced so far for climate-related spending in the wake of the pandemic, according to a new analysis from green groups.
U.S. President Joe Biden is contemplating a climate and clean energy recovery plan that could “exceed US$2 trillion,” White House officials told reporters this month. “Per capita, that is over eight times what Canada has announced so far for climate-related spending in the wake of the pandemic,” the IISD-led analysis stated.

Biden’s election platform commitment of $508 billion over 10 years in clean energy was also seen as “significantly higher per capita than Canada’s recent commitments.”

Since October 2020, Canada has announced $36 billion in new climate-focused funding, a 2035 EV mandate and other measures, the groups found. By comparison, they noted, a political agreement in Europe proposed that a minimum of 37 per cent of investments in each national recovery plan should support climate action. France and Germany have also committed tens of billions of dollars to support clean hydrogen.

As for electric vehicles (EVs), the United Kingdom has committed $4.9 billion, while Germany has put up $7.5 billion to expand EV adoption and charging infrastructure and sweeten incentive programs for prospective buyers, complementing Canada’s ambitious EV goals announced domestically. The U.K. has also committed $3.5 billion for bike lanes and other active transportation, the groups noted.

Canada announced $400 million over five years this month for a new network of bike lanes, paths, trails and bridges, the first federal fund dedicated to active transportation.

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U.S. Offshore Wind Power Strategy leverages UK offshore wind lessons, contract auctions, and supply chains to scale renewable energy, build wind farms, cut emissions, create jobs, and modernize the grid to meet 2030 climate goals.

Key Points

U.S. plan to scale offshore wind via UK-style contracts, turbines, and supply chains to meet 2030 clean energy goals

✅ Contract-for-difference price guarantees de-risk projects

✅ Scale turbines and ports to cut LCOE and boost capacity

✅ Build coastal grids, transmission, and workforce by 2030

As President Joe Biden’s administration puts its muscle behind wind power with plans to develop large-scale wind farms along the entire United States coastline, the administration can look at how the windiest nation in Europe is transforming its energy grid for an example of how to proceed.

In the search for renewable sources of energy, the United Kingdom has embraced wind power. In 2020, the country generated as much as 24 percent of its electricity from wind power across the grid — enough to supply 18.5 million homes, according to government statistics. 

With usually reliable winds, the U.K. currently has the highest number of offshore turbines installed in the world, with China at a close second.

Experts and industry leaders say it offers valuable lessons on creating a viable market for wind power at the ambitious scale the Biden administration hopes to meet in order to confront climate change and help transition the U.S. economy to renewable energy.

“The U.S. is going to benefit hugely from the early investment that European governments have put into offshore wind,” said Oliver Metcalfe, a wind power analyst at BloombergNEF in London, an independent research group.

Big American plans
On Oct. 13, the White House announced ambitious offshore wind plans to lease federal waters off of the East and West Coasts and Gulf of Mexico to develop commercial wind farms.

The move is part of Biden’s goal to have 30,000 megawatts of offshore wind power produced in the United States by 2030, with projects such as New York's record-setting approval highlighting the momentum. The White House says that would generate enough electricity to power more than 10 million homes and in the process create 77,000 jobs. 

But there is a chasm between where the U.S. is now and where it wants to be within the next decade when it comes to offshore wind power.

“We’re the first generation to understand the science and implications of climate change and we’re the last generation to be able to do something about it.”

The U.S. is not new to wind power; onshore wind in states such as Texas, Oklahoma and Iowa supplied 8.2 percent of the country’s total electricity generation in 2020, according to the U.S. Department of Energy. 

But despite its long coastlines, offshore wind has been a largely untapped resource in the U.S. With a population of about 332 million people, the U.S. currently has just two operational offshore wind farms — off Rhode Island and Virginia — with the capacity to produce 42 megawatts of electricity between them, far from the 1 gigawatt on-grid milestone many are watching. 

In contrast, the U.K., with a population of 67 million people, has 2,297 offshore wind turbines with the capacity to produce 10,415 megawatts of electricity.

Power station or a park?
Just outside of central Glasgow, the host city for the U.N. climate change conference known as COP26, the fruits of years of effort to move away from fossil fuels can be seen and heard

International financiers, including the World Bank are helping developing countries scale wind projects to meet climate goals.

Whitelee Windfarm, the U.K.’s largest onshore wind farm, spreads across 30 square miles on the Eaglesham Moor and includes more than 80 miles of trails for walking, cycling and horseback riding.

With its 539 megawatt capacity, it generates enough electricity for 350,000 homes — more than half the population of Glasgow. 

On a recent gusty fall day, Ian and Fiona Gardner, both 71, were walking their dogs among the wind farm’s 360-foot-tall turbines  

“This is a major contribution to Scotland, to become independent from oil by 2035,” Ian Gardner, an accountant, said. 

Thanks to the rapid technological advances in turbine technology, this wind farm that was completed in 2009, is now practically old school. The latest crop of onshore turbines typically generate double the current capacity of Whitelee’s turbines.

“It took us 20 years to build 2 gigawatts of power. And we’re going to double that in five  years,” said McQuade, an economist. “We can do that because machines are big, efficient, cheap and the supply chain is there.” 

The biggest operational offshore wind farm in the world right now, Hornsea Project One, is about 75 miles off England’s Yorkshire coast in the North Sea.

Owned and operated by Orsted, a former Danish oil and gas giant, in partnership with Global Infrastructure Partners, its 174 turbines have the capacity to generate 1.2 gigawatts — enough to power over 1 million homes and roughly equivalent to a nuclear power plant. 

Benj Sykes, Vice President of U.K. Offshore Wind at Orsted, called Hornsea One a “game changer” in a recent phone interview, citing it as an example of how the industry has scaled up its output to compete with traditional power plants.

But massive projects like Hornsea One took decades to get up and running, as well as government help. According to Malte Jansen, a research associate at the Centre of Environmental Policy at Imperial College London, the British government helped facilitate a “paradigm shift” in renewable energy in 2013.

The electricity market reform policy set up a framework to incentivize investment in offshore wind farms by creating an auction system that guarantees electricity prices to developers in 15-year contracts, alongside new contract awards that add 10 GW to the U.K. grid. 

This means there is no upside in terms of market price fluctuation, but there is no downside either. The policy essentially “de-risked the investment,” Jansen said.

The state contracts allowed the industry to innovate and learn how to develop even larger and more efficient turbines with blades that stretch as long as 267 feet, about three-quarters the size of a U.S. football field. 

While this approach helped companies and investors, it will also have an unintended beneficiary — the U.S., Metcalfe from BloombergNEF said. 

Developers are “taking the lessons they’ve learned building projects in Europe, the cost reductions that they’ve achieved building projects in Europe and are now bringing those to the U.S. market,” he said.

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Electric Car Motors convert electricity to torque via rotor-stator magnetic fields, using AC/DC inverters, permanent magnets or induction designs; they power EV powertrains efficiently and enable regenerative braking for energy recovery and control.

Key Points

Electric car motors turn electrical energy into wheel torque using rotor-stator fields, inverters, and AC or DC control.

✅ AC induction, PMSM, BLDC, and reluctance architectures explained

✅ Inverters manage AC/DC, voltage, and motor speed via frequency

✅ Regenerative braking recovers energy and reduces wear

When was the last time you stopped to think about how electric cars actually work, especially if you're wondering whether to buy an electric car today? We superfans of the car biz have mostly developed a reasonable understanding of how combustion powertrains work. Most of us can visualize fuel and air entering a combustion chamber, exploding, pushing a piston down, and rotating a crankshaft that ultimately turns the wheels. We generally understand the differences between inline, flat, vee-shaped, and maybe even Wankel rotary combustion engines.

Mechanical engineering concepts such as these are comparatively easy to comprehend. But it's probably a fair bet to wager that only a minority of folks reading this can explain on a bar napkin exactly how invisible electrons turn a car's wheels or how a permanent-magnet motor differs from an AC induction one. Electrical engineering can seem like black magic and witchcraft to car nuts, so it's time to demystify this bold new world of electromobility, with the age of electric cars arriving ahead of schedule.

How Electric Cars Work: Motors
It has to do with magnetism and the natural interplay between electric fields and magnetic fields. When an electrical circuit closes allowing electrons to move along a wire, those moving electrons generate an electromagnetic field complete with a north and a south pole. When this happens in the presence of another magnetic field—either from a different batch of speeding electrons or from Wile E. Coyote's giant ACME horseshoe magnet, those opposite poles attract, and like poles repel each other.

Electric motors work by mounting one set of magnets or electromagnets to a shaft and another set to a housing surrounding that shaft. By periodically reversing the polarity (swapping the north and south poles) of one set of electromagnets, the motor leverages these attracting and repelling forces to rotate the shaft, thereby converting electricity into torque and ultimately turning the wheels, in a sector where the electric motor market is growing rapidly worldwide. Conversely—as in the case of regenerative braking—these magnetic/electromagnetic forces can transform motion back into electricity.

How Electric Cars Work: AC Or DC?
The electricity supplied to your home arrives as alternating current (AC), and bidirectional charging means EVs can power homes for days as needed, so-called because the north/south or plus/minus polarity of the power changes (alternates) 60 times per second. (That is, in the United States and other countries operating at 110 volts; countries with a 220-volt standard typically use 50-Hz AC.) Direct current (DC) is what goes into and comes out of the + and - poles of every battery. As noted above, motors require alternating current to spin. Without it, the electromagnetic force would simply lock their north and south poles together. It's the cycle of continually switching north and south that keeps a motor spinning.

Today's electric cars are designed to manage both AC and DC energy on board. The battery stores and dispenses DC current, but again, the motor needs AC. When recharging the battery, and with increasing grid coordination enabling flexibility, the energy comes into the onboard charger as AC current during Level 1 and Level 2 charging and as DC high-voltage current on Level 3 "fast chargers." Sophisticated power electronics (which we will not attempt to explain here) handle the multiple onboard AC/DC conversions while stepping the voltage up and down from 100 to 800 volts of charging power to battery/motor system voltages of 350-800 volts to the many vehicle lighting, infotainment, and chassis functions that require 12-48-volt DC electricity.

How Electric Cars Work: What Types Of Motors?
DC Motor (Brushed): Yes, we just said AC makes the motor go around, and these old-style motors that powered early EVs of the 1900s are no different. DC current from the battery is delivered to the rotor windings via spring-loaded "brushes" of carbon or lead that energize spinning contacts connected to wire windings. Every few degrees of rotation, the brushes energize a new set of contacts; this continually reverses the polarity of the electromagnet on the rotor as the motor shaft turns. (This ring of contacts is known as the commutator).

The housing surrounding the rotor's electromagnetic windings typically features permanent magnets. (A "series DC" or so-called "universal motor" may use an electromagnetic stator.) Advantages are low initial cost, high reliability, and ease of motor control. Varying the voltage regulates the motor's speed, while changing the current controls its torque. Disadvantages include a lower lifespan and the cost of maintaining the brushes and contacts. This motor is seldom used in transportation today, save for some Indian railway locomotives.

Brushless DC Motor (BLDC): The brushes and their maintenance are eliminated by moving the permanent magnets to the rotor, placing the electromagnets on the stator (housing), and using an external motor controller to alternately switch the various field windings from plus to minus, thereby generating the rotating magnetic field.

Advantages are a long lifespan, low maintenance, and high efficiency. Disadvantages are higher initial cost and more complicated motor speed controllers that typically require three Hall-effect sensors to get the stator-winding current phased correctly. That switching of the stator windings can result in "torque ripple"—periodic increases and decreases in the delivered torque. This type of motor is popular for smaller vehicles like electric bikes and scooters, and it's used in some ancillary automotive applications like electric power steering assist.

Permanent-Magnet Synchronous Motor (PMSM): Physically, the BLDC and PMSM motors look nearly identical. Both feature permanent magnets on the rotor and field windings in the stator. The key difference is that instead of using DC current and switching various windings on and off periodically to spin the permanent magnets, the PMSM functions on continuous sinusoidal AC current. This means it suffers no torque ripple and needs only one Hall-effect sensor to determine rotor speed and position, so it's more efficient and quieter.

The word "synchronous" indicates the rotor spins at the same speed as the magnetic field in the windings. Its big advantages are its power density and strong starting torque. A main disadvantage of any motor with spinning permanent magnets is that it creates "back electromotive force" (EMF) when not powered at speed, which causes drag and heat that can demagnetize the motor. This motor type also sees some duty in power steering and brake systems, but it has become the motor design of choice in most of today's battery electric and hybrid vehicles.

Note that most permanent-magnet motors of all kinds orient their north-south axis perpendicular to the output shaft. This generates "radial (magnetic) flux." A new class of "axial flux" motors orients the magnets' N-S axes parallel to the shaft, usually on pairs of discs sandwiching stationary stator windings in between. The compact, high-torque axial flux orientation of these so-called "pancake motors" can be applied to either BLDC or PMSM type motors.

AC Induction: For this motor, we toss out the permanent magnets on the rotor (and their increasingly scarce rare earth materials) and keep the AC current flowing through stator windings as in the PMSM motor above.

Standing in for the magnets is a concept Nikola Tesla patented in 1888: As AC current flows through various windings in the stator, the windings generate a rotating field of magnetic flux. As these magnetic lines pass through perpendicular windings on a rotor, they induce an electric current. This then generates another magnetic force that induces the rotor to turn. Because this force is only induced when the magnetic field lines cross the rotor windings, the rotor will experience no torque or force if it rotates at the same (synchronous) speed as the rotating magnetic field.

This means AC induction motors are inherently asynchronous. Rotor speed is controlled by varying the alternating current's frequency. At light loads, the inverter controlling the motor can reduce voltage to reduce magnetic losses and improve efficiency. Depowering an induction motor during cruising when it isn't needed eliminates the drag created by a permanent-magnet motor, while dual-motor EVs using PMSM motors on both axles must always power all motors. Peak efficiency may be slightly greater for BLDC or PMSM designs, but AC induction motors often achieve higher average efficiency. Another small trade-off is slightly lower starting torque than PMSM. The GM EV1 of the mid-1990s and most Teslas have employed AC Induction motors, despite skepticism about an EV revolution in some quarters.

Reluctance Motor: Think of "reluctance" as magnetic resistance: the degree to which an object opposes magnetic flux. A reluctance motor's stator features multiple electromagnet poles—concentrated windings that form highly localized north or south poles. In a switched reluctance motor (SRM), the rotor is made of soft magnetic material such as laminated silicon steel, with multiple projections designed to interact with the stator's poles. The various electromagnet poles are turned on and off in much the same way the field windings in a BLDC motor are. Using an unequal number of stator and rotor poles ensures some poles are aligned (for minimum reluctance), while others are directly in between opposite poles (maximum reluctance). Switching the stator polarity then pulls the rotor around at an asynchronous speed.

A synchronous reluctance motor (SynRM) doesn't rely on this imbalance in the rotor and stator poles. Rather, SynRM motors feature a more distributed winding fed with a sinusoidal AC current as in a PMSM design, with speed regulated by a variable-frequency drive, and an elaborately shaped rotor with voids shaped like magnetic flux lines to optimize reluctance.

The latest trend is to place small permanent magnets (often simpler ferrite ones) in some of these voids to take advantage of both magnetic and reluctance torque while minimizing cost and the back EMF (or counter-electromotive force) high-speed inefficiencies that permanent-magnet motors suffer.

Advantages include lower cost, simplicity, and high efficiency. Disadvantages can include noise and torque ripple (especially for switched reluctance motors). Toyota introduced an internal permanent-magnet synchronous reluctance motor (IPM SynRM) on the Prius, and Tesla now pairs one such motor with an AC induction motor on its Dual Motor models. Tesla also uses IPM SynRM as the single motor for its rear-drive models.

Electric motors may never sing like a small-block or a flat-plane crank Ferrari. But maybe, a decade or so from now, we'll regard the Tesla Plaid powertrain as fondly as we do those engines, even as industry leaders note that mainstream adoption faces hurdles, and every car lover will be able to describe in intimate detail what kind of motors it uses.
 

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