diff --git a/motor/README.md b/motor/README.md index b60e1b5..e0a7319 100644 --- a/motor/README.md +++ b/motor/README.md @@ -1,11 +1,301 @@ -# Motor Research +# Motor Research (Apr 24, 2026) +## Liquid-Cooled Small BLDC Motor (β‰ˆ30 mm) β€” Research Sheet +## Focus: Internal Channel / Directed Cooling (Concept B) + +--- + +# 🧠 1. Objective + +Design a **high power-density, continuous-duty BLDC motor (~30 mm class)** for EDF/prop aircraft using: + +> **Directed internal cooling channels through the stator (not full immersion)** + +Goal: +- Maximize **continuous power** +- Maintain **high efficiency at very high RPM (30k–100k)** +- Avoid fluid drag losses from rotor immersion + +--- + +# βš™οΈ 2. Core Concept (B) + +### Definition +A motor where: +- Coolant flows through **engineered paths inside the stator** +- Heat is removed **directly from windings and core** +- Rotor remains **dry (air-filled cavity)** + +--- + +## 🧩 2.1 Cooling Architecture Types + +### A. Axial Channels (through stator stack) +- Holes or ducts aligned with shaft axis +- Coolant enters one end, exits the other + +### B. Slot-Integrated Cooling +- Channels embedded near winding slots +- Coolant flows alongside copper + +### C. Back-Iron Cooling +- Channels placed in stator back iron +- Lower impact on copper fill, but less direct + +--- + +# πŸ”₯ 3. Thermal Model + +### Heat Sources +- Copper losses: + \[ + P_{cu} = I^2 R + \] + +- Core losses: + - hysteresis + - eddy currents + +--- + +### Cooling Mechanism +Convective heat transfer: +\[ +Q = h \cdot A \cdot \Delta T +\] + +Where: +- \( h \) = heat transfer coefficient (high for liquid) +- \( A \) = channel surface area +- \( \Delta T \) = temp difference + +--- + +## πŸ“Š Expected Thermal Performance + +| Coolant Temp | Winding Temp | Ξ”T | Notes | +|--------------|-------------|----|------| +| 30Β°C | 40–60Β°C | ~10–30Β°C | Moderate cooling | +| 20Β°C | 35–50Β°C | ~10–25Β°C | Strong | +| 10Β°C | 25–40Β°C | ~10–20Β°C | Very strong | +| 5Β°C | 20–35Β°C | ~10–15Β°C | Diminishing returns | + +--- + +# ⚑ 4. Electromagnetic Tradeoffs (Critical) + +## ❗ 4.1 Reduced Copper Fill + +Channels take space β†’ less copper: + +- ↑ Resistance (R) +- ↑ Copper losses +- ↓ Torque per amp + +--- + +## ❗ 4.2 Reduced Iron Cross-Section + +Channels remove stator material: + +- ↓ Magnetic flux capacity +- ↑ Risk of saturation +- ↓ Maximum torque + +--- + +## βš–οΈ Tradeoff Summary + +| Parameter | Effect | +|----------|-------| +| Cooling | ↑↑ | +| Resistance | ↑ | +| Torque density | ↓ | +| Efficiency (if optimized) | ↑ overall | + +--- + +# πŸŒ€ 5. Fluid Design Considerations + +## βœ”οΈ Goals +- Maximize heat extraction +- Minimize pressure drop +- Ensure uniform distribution + +--- + +## ❗ Constraints + +### 1. Channel Size +- Too small β†’ high pressure drop +- Too large β†’ weak stator + lost copper + +--- + +### 2. Flow Regime +- Laminar β†’ predictable, less transfer +- Turbulent β†’ better cooling, higher loss + +--- + +### 3. Pressure Drop +\[ +\Delta P \propto \frac{L \cdot v^2}{D} +\] + +Impacts: +- pump requirements +- system efficiency + +--- + +# 🧲 6. Magnetic Design Constraints + +## Saturation Limit +Even with perfect cooling: + +- Core saturates at high flux +- Current increase β†’ diminishing torque + +--- + +## Design Implication +You must balance: +- channel placement +- iron thickness +- slot geometry + +--- + +# βš™οΈ 7. Mechanical Constraints + +## 7.1 Structural Integrity +Channels weaken stator: +- risk of deformation +- vibration issues at high RPM + +--- + +## 7.2 Sealing +Unlike concept A: +- sealing is localized (inlet/outlet) +- not full rotor enclosure + +--- + +## 7.3 Weight +Added: +- coolant +- tubing +- pump + +Must not exceed thrust gains + +--- + +# πŸš€ 8. Performance Expectations + +## Compared to Air-Cooled Motor + +| Metric | Improvement | +|-------|------------| +| Continuous current | ~1.8–2.3Γ— | +| Continuous power | ~2.5–4Γ— | +| Efficiency | ↑ (if well designed) | +| Peak temp | ↓ significantly | + +--- + +# 🧠 9. Key Design Strategy + +## πŸ”‘ Optimize for: +- Minimal disruption of magnetic path +- Maximum contact with windings +- Controlled coolant flow + +--- + +## ❌ Avoid: +- Large voids in stator +- Random channel placement +- Overcomplicated routing + +--- + +# πŸ§ͺ 10. Recommended Cooling Fluids + +| Fluid | Pros | Cons | +|------|------|------| +| Dielectric oil | Safe, good cooling | Viscosity | +| Water-glycol | Excellent heat capacity | Conductive risk | +| Fluorinated fluids | Ideal electrically | Expensive | + +--- + +# ⚑ 11. System-Level Optimization + +## Important Shift: + +> Cooling allows higher current, but optimal design reduces current + +--- + +### Best Practices: +- Lower KV motor +- Higher voltage supply +- Thicker windings +- Maximize slot fill before adding channels + +--- + +# 🧩 12. Hybrid Enhancement (Best Approach) + +Combine: +- Partial channel cooling (B) +- Directed oil spray (controlled A) + +Avoid: +- full immersion + +--- + +# πŸ“Œ 13. Final Engineering Insight + +> Concept B does not give β€œfree performance” + +It trades: +- electromagnetic efficiency +for +- thermal headroom + +--- + +## 🏁 Conclusion + +For ~30 mm EDF motors: + +βœ” Internal channel cooling is **more viable than immersion** +βœ” Enables large continuous power gains +❗ Must be carefully balanced against magnetic losses + +--- + +# πŸ” 14. Future Exploration + +- Additive manufacturing stators +- Micro-channel cooling +- Slot liner cooling integration +- Oil jet targeting windings only + +--- + +# Motor Research (Jul 20, 2025) The research for better motor tech. We will be comparing between different kinds of motors in order to gain a better understanding of them. ### Priorities - **Efficiency**: Current efficiency range (70/87%), goal (90-95%), efficiency is measured in output power (rpm/torque) per watt. - **Reliability**: Withstand a long duration of high throttle and extreme conditions of weather. ## BLDC vs PMSM -| Feature | **BLDC (Brush-less DC Motor)** | **PMSM (Permanent Magnet Synchronous Motor)** | +| Feature | **BLDC (Brush-less DC Motor)** | **PMSM (Permanent Magnet Synchronous Motor)** | | ------------------------ | -------------------------------------- | ----------------------------------------------- | | **Rotor** | Permanent magnets | Permanent magnets | | **Stator winding** | Trapezoidal | Sinusoidal | @@ -20,4 +310,4 @@ The research for better motor tech. We will be comparing between different kinds BLDC motor ## PMSM - Permanent Magnet Synchronous Motor -PMSM motor \ No newline at end of file +PMSM motor