HRIM Motor — Hybrid Reluctance Induction Motor
Every induction motor ever built throws away half of the magnetic flux it creates. The HRIM Motor is the first design to catch that lost half and put it to work — extra torque, self-cooling and continuous energy recovery from the same power input.
Extra torque
Uses 100% of the magnetic flux instead of 50%, so the same current produces more torque and speed. Measured on the prototype: +0.34 Nm on top of the base torque.
Fanless cooling
The outer rotor is shaped like a blower impeller. It cools the stator directly as it spins, so the conventional cooling fan can be removed entirely.
Energy recovery
A built-in generator assembly harvests power the whole time the motor runs — from the moment it starts until it stops — not only during braking.
How the HRIM Motor evolved
A 130-year-old motor with a hidden leak
The three-phase induction motor has powered industry since the 1890s. It is cheap, rugged and almost maintenance-free, which is why it still drives pumps, compressors, conveyors and, increasingly, electric vehicles. But it carries a flaw that has been accepted for so long that most engineers stopped noticing it.
When polyphase current flows through the stator windings, it creates a rotating magnetic field. Only half of that flux (Ø/2) lives inside the stator cavity where the rotor can use it. The other half (Ø/2) escapes outward through the stator core — doing no work, and worse, heating up the motor body. Every induction motor on Earth then bolts a fan onto the shaft to blow that waste heat away, spending yet more energy to deal with energy it already wasted.
Why the market was ready for something new
By the late 2010s the motor market was changing fast. Minimum Energy Performance Standards (MEPS) were being adopted worldwide and IE2 and IE3 efficiency classes were becoming the norm. In India, the push toward hybrid and electric vehicles created a demand for inexpensive, high-efficiency motors that could also recover energy. Earlier designs tackled parts of the problem — squirrel-cage motors tuned for EVs (IN 332228 A1) and dual-stator induction-synchronous machines (US 5254894 A) — but none of them touched the root cause: the unused half of the flux.
The question that started everything
That question became the whole invention. The answer was a second rotor — mounted outside the stator body on a bearing, fitted with permanent magnets on its teeth. The magnets sit at 90° to the stray rotating field so they achieve the maximum “flux cut”. As the field rotates, the reluctance force between the permanent magnets and the field drags the outer rotor around with it. The leaked Ø/2 flux, wasted for over a century, now produces torque.
The name follows from the physics: an induction motor on the inside and a reluctance motor on the outside — a Hybrid Reluctance Induction Motor.
Turning the rotor into its own fan
Once an outer rotor was spinning around the stator, a second idea followed naturally. Why not shape it like a blower impeller? Each tooth was designed with an air gap between it and the next, so that as the outer rotor spins it pulls air across the entire stator body. The motor now cools itself directly at the source of heat — far more effectively than a small fan on the end of the shaft — and the induction fan can be removed altogether.
A motor that gives power back
The outer rotor is covered in permanent magnets and it spins whenever the motor runs. That is exactly what an alternator needs. So a third layer was added: an outermost system of coils, each wound around a laminated core, arranged like an alternator stator over the outer rotor. As the magnets sweep past these coils they generate electricity — continuously, from start-up to shutdown, not just during braking as in a normal regenerative system.
Three parts, one machine: a conventional squirrel-cage rotor inside the stator, a permanent-magnet impeller rotor outside it, and a generator coil assembly outside that. Together they use the whole flux, cool the motor, and recover energy — while keeping every advantage that made the induction motor great in the first place.
Proof on the bench
Theory is cheap; a prototype is not. A working HRIM1 prototype (2-pole, 0.5 HP, 220 V) was built and driven from a variable-frequency drive. The key test was simple: lock the outer rotor by hand (“normal condition”) and compare against letting it run freely (“with arrangement”). If the outer rotor drew extra current, the idea would be a fraud. If it spun on the leaked flux alone, the idea worked.
| Measurement | Outer rotor locked | Outer rotor free (HRIM) | Conclusion |
|---|---|---|---|
| Input current per phase at 10 Hz | ≈ 0.133 – 0.139 A | ≈ 0.132 – 0.139 A | No extra current drawn — the outer rotor is driven by flux that was already being wasted. |
| Stator temperature after 5 min at 10 Hz | 40.3 °C (42.7 °C at 6 min) | 35.7 °C (only 41.9 °C after 40 min) | The impeller rotor keeps the motor cool; the shaft fan is redundant. |
| Base torque at 10 Hz | 0.79 Nm | Standard induction-motor torque. | |
| Extra torque from outer rotor | — | 0.34 Nm (at 50 Hz, 2:1 mechanical advantage) | Additional torque produced entirely by the recovered flux, with no extra current. |
| Speed at 50 Hz | 4,000 rpm | Above the 3,000 rpm synchronous speed of a conventional 2-pole machine. | |
| Generator output | — | ≈ 12 V continuous | Power recovered throughout the run, with phase current unchanged. |
Recognition
The invention was filed with the Indian Patent Office by Shirshendu Sasmal and granted as Patent No. 555489 on 22 March 2023, with ten claims covering the dual-rotor arrangement, the 90° permanent-magnet placement, the impeller-shaped outer rotor and the integrated power-generating assembly. It is the founding technology of EcoSanskriti Innovations.
Where it goes next
The HRIM principle is not tied to one size of motor. The same three-layer architecture can be applied to any polyphase machine:
At a glance
| Type | 3-phase AC hybrid reluctance induction motor |
| Inner rotor | Squirrel-cage induction rotor inside the stator cavity (uses Ø/2 cavity flux) |
| Outer rotor | Permanent-magnet reluctance rotor mounted over the stator body on a bearing; impeller-shaped teeth with air gaps (uses Ø/2 core-leakage flux) |
| Magnet placement | 90° to the external rotating field for maximum flux cut |
| Generator assembly | Outermost system of coils on laminated cores, alternator-style |
| Cooling | Direct stator cooling by the impeller rotor — no shaft fan |
| Prototype tested | HRIM1 — 2-pole, 0.5 HP, 220 V, VFD-driven |
| Applications | Electric & hybrid vehicles, industrial machinery |
| Patent | India No. 555489 · Granted 22 March 2023 · 10 claims |
| Inventor | Shirshendu Sasmal |
Interested in licensing, manufacturing or investing?
We are looking for partners to take the HRIM Motor from prototype to production — for electric vehicles, industry and green mobility.