Electric motors are the most important machines humanity has ever built.
This is not hyperbole. Electric motors — in their many forms — consume approximately 45% of global electricity. Industrial motors alone account for 28% of global electricity demand. The total installed base exceeds 50 billion units, ranging from the micro-motors in your phone’s camera actuator to the 20 MW propulsion motors on large cargo ships.
A 1% improvement in average motor efficiency would reduce global electricity consumption by roughly 200 TWh per year — equivalent to the entire annual output of 25 large coal power plants.
This is why motor efficiency is not a niche engineering topic. It is one of the highest-leverage opportunities in sustainable engineering — and it is why companies like Entlar, focused on BLDC motor technology, are working on something that matters.
Where Energy Is Lost in an Electric Motor
To design an efficient motor, you need to understand where energy is lost. Motor losses fall into five categories:
1. Copper Losses (I²R)
Joule heating in the winding resistance. This is the dominant loss in most motors, particularly at high load. Proportional to current squared — which means:
- Every doubling of current quadruples copper losses
- Operating at rated current is the worst case
- Partial-load efficiency is critical for real-world energy consumption
Reduction strategies:
- Lower winding resistance (larger wire cross-section, shorter mean turn length, higher slot fill factor)
- Hairpin windings: laser-welded flat copper conductors with 70–80% slot fill versus 40–50% for round wire. Standard in EV traction motors, increasingly used in high-efficiency industrial motors.
- Operating at lower current by using a higher-voltage motor for the same power output
2. Iron Losses (Core Losses)
Hysteresis and eddy current losses in the stator and rotor laminations. These losses depend on the flux density and frequency of flux variation.
Hysteresis loss is proportional to frequency and flux density squared. Eddy current loss is proportional to frequency squared and lamination thickness squared.
Reduction strategies:
- Thinner laminations (0.1–0.2 mm versus standard 0.35–0.5 mm). Cost increases significantly.
- High-silicon electrical steel (3–6.5% Si) with lower hysteresis loss coefficient
- Amorphous metal alloys (Metglas): iron loss 75% lower than silicon steel, but challenging to stamp and laminate at scale
- Operating at lower flux density (achieved by increasing motor volume for same torque output)
3. Mechanical Losses
Friction and windage losses. Bearing friction, air resistance of the rotating parts. Typically 1–3% of rated power.
Reduction strategies:
- Ceramic hybrid bearings (steel balls, ceramic rings): lower coefficient of friction, significantly reduced thermal conductivity from inner to outer race (reducing thermal grease requirements)
- Smooth rotor surface finish (reduced windage)
- Internal fan elimination where external cooling is used instead
4. Stray Load Losses
A catch-all for losses that do not fit neatly into the above categories: harmonic content in the stator current (from PWM switching), slot leakage flux losses, surface losses from high-order harmonics. Typically 1–2% of rated power, but larger in inverter-fed motors.
Reduction strategies:
- Higher PWM switching frequency (reduces current ripple, reduces harmonic losses in windings)
- Distributed windings with fractional pitch (reduces harmonic air gap flux)
- Proper inverter tuning (minimise current THD)
5. Inverter Losses
In a variable-speed drive, the inverter itself has conduction and switching losses. These are not motor losses per se, but they affect system efficiency.
At 48V and 20A (960W), a typical SiC MOSFET inverter at 20 kHz switching frequency has approximately 15–25W of inverter losses — representing 1.5–2.5% of power. Silicon IGBT-based inverters at the same operating point are significantly higher.
Efficiency Standards and Their Impact
Motor efficiency standards have been one of the most effective energy policy tools of the last two decades.
The IEC 60034-30 standard defines efficiency classes:
- IE1: Standard efficiency (~82% at 4 kW)
- IE2: High efficiency (~85% at 4 kW)
- IE3: Premium efficiency (~88% at 4 kW)
- IE4: Super-premium efficiency (~91% at 4 kW)
- IE5: Ultra-premium efficiency (~93% at 4 kW)
Mandatory minimum efficiency requirements have progressively tightened. The EU currently mandates IE3 for motors above 0.75 kW in industrial applications. IE4 and IE5 targets are under discussion for 2027–2030.
The regulatory trajectory is clear: motor efficiency will continue to be regulated upward. Engineers designing motors or systems containing motors need to plan for IE4/IE5 compliance in new designs, even where IE3 is the current requirement.
BLDC vs AC Induction: The Efficiency Case
The shift from AC induction motors (ACIM) to permanent-magnet synchronous motors (PMSM/BLDC) is the dominant efficiency improvement available in many applications:
| Parameter | ACIM (IE2) | ACIM (IE3) | BLDC/PMSM (IE4+) |
|---|---|---|---|
| Peak efficiency | 85% | 88% | 93–96% |
| Part-load efficiency | Poor | Moderate | Excellent |
| Standby losses | High | High | Low |
| Variable speed efficiency | Degrades | Degrades | Maintained |
The part-load and variable-speed efficiency differences are critical in real-world applications. A motor running at 50% load for most of its operating hours — which is typical in HVAC, pumps, and fans — loses dramatically more energy in ACIM designs versus BLDC.
Entlar’s Efficiency Targets
Our ceiling fan BLDC motor targets:
- System efficiency (motor + drive) at rated speed: ≥92%
- System efficiency at 50% speed: ≥88% (fans are particularly sensitive to part-load efficiency because of the cubic relationship between fan power and speed)
- Standby current (BLE radio active, motor off): <50 mW
- Annual energy consumption at typical usage pattern (6 hours/day at 70% speed): <35 kWh
For context, a standard AC induction ceiling fan consumes 45–75W at full speed. Our BLDC fan achieves equivalent airflow at 28–35W. At 6 hours/day, 365 days/year, that is 53–109 kWh versus 41–51 kWh — a 25–35% annual energy saving per fan.
In a typical Indian office with 20 ceiling fans running 10 hours/day, the annual savings exceed 1,200 kWh — approximately ₹9,600 at commercial electricity rates.
Sustainable Engineering Is Efficiency Engineering
The motor efficiency problem is a microcosm of sustainable engineering in general. The highest-leverage sustainability interventions are rarely about exotic new materials or disruptive new technologies. They are about applying existing physics knowledge rigorously to designs that have historically been built to a cost, not to an efficiency target.
Better insulation materials, thinner laminations, higher-quality permanent magnets, optimised winding geometries — none of this is exotic. All of it requires engineering discipline and willingness to invest in design quality.
At Entlar, we believe that the most important engineering work is not the work that makes headlines. It is the quiet, rigorous work of pushing established technology to its physical limits — and demonstrating that efficiency and cost-competitiveness are not in opposition.
They are the same goal.