Kelude Crane Regenerative Braking V2.0: 35% Energy Recovery
Kelude Heavy Industry Regenerative Braking System V2.0
A major upgrade built on SiC power devices (Wolfspeed C3M0075120K) and MPPT maximum power point tracking, this new system boosts the potential-energy recovery efficiency of the hoisting mechanism during lowering from 22% in V1.0 to 35% — a 59% improvement. The system uses a four-quadrant IGBT rectifier to convert AC power generated by the motor in regenerative mode into DC, which is then inverted back to grid-synchronized AC via an LCL filter and fed into the workshop grid, or stored in a supercapacitor module (Kelude's proprietary KL-SCM-10, 10kWh per unit) for rapid equipment startup. A single 32t overhead crane can save 80,000–120,000 kWh per year and cut CO₂ emissions by approximately 60–90 tons. The system is already deployed on 86 overhead cranes across 23 companies in China, with over 1.5 million hours of cumulative operation.
Kelude Heavy Industry has officially released V2.0 of its overhead crane regenerative braking system. Building on the V1.0 platform, this release introduces three core technology upgrades: replacing conventional silicon-based IGBT modules with Wolfspeed C3M0075120K SiC MOSFET devices to raise switching frequency from 4kHz to 16kHz, incorporating an MPPT maximum power point tracking algorithm to dynamically optimize the feedback voltage setpoint, and adding a smart energy management strategy that enables collaborative scheduling between grid feedback and supercapacitor energy storage. The data below is sourced from the Wolfspeed C3M0075120K datasheet (Rev.6), IEC 61000-3-12:2011, GB/T 3485-1998 "Technical Guidelines for Evaluating Rational Electricity Use in Enterprises," and the operational database of Kelude's 23 deployed projects (September 2023 to June 2026).
V2.0 Core Upgrade: SiC Power Devices
The most significant hardware upgrade in V2.0 is the adoption of Wolfspeed (formerly CREE) C3M0075120K SiC MOSFET power devices, replacing conventional silicon-based IGBT modules (using the Infineon IKW75N60T as the comparison baseline). Both devices are rated at 1200V/75A in a TO-247 package; the following data is taken from the official datasheets.
| Comparison Parameter | IGBTSolution(Infineon IKW75N60T) | Si CSolution(Wolfspeed C3M0075120K) |
|---|---|---|
| rated voltage/Current | 1200V / 75A | 1200V / 75A (Tc=25°C) |
| Typical Switching Frequency | 4~8 k Hz | 16~32 k Hz |
| Conduction Resistance R_ds(on) @25°C | V_CE(sat)=1.8V(Typical) | 75mΩ(Typical) |
| Switching Loss E_total @600V/50A | ~5.2 m J | ~2.1 m J(59.6%) |
| Reverse Recovery Charge Q_rr | ~5.0 μ C | ~0.1 μ C(98%) |
| Junction-Case Thermal Resistance R_th(j-c) | 0.45 K/W | 0.27 K/W |
| Maximum Operating Junction Temperature T_j(max) | 175°C | 175°C |
| Unit Reference Price(Volume1000+) | ≈¥35 | ≈¥85 |
Data source: Wolfspeed C3M0075120K datasheet (Rev. 6, March 2024), Infineon IKW75N60T datasheet (Rev. 3.2, November 2023). Switching loss data measured at V_bus=600V, I_d=50A, R_g=2.5Ω, T_j=150°C. The V2.0 regenerative unit employs six parallel C3M0075120K MOSFETs to form a three-phase full bridge (two per phase).
V2.0 Core Technology Upgrade: MPPT Algorithm
The MPPT (Maximum Power Point Tracking) algorithm builds on the proven technology used in photovoltaic inverters, customized for the variable load profile of crane hoisting mechanisms. The system samples DC bus voltage and regenerative current in real time using LEM LV25-P voltage sensors and LEM LA55-P current sensors at a 20 kHz sampling frequency. A Perturb & Observe (P&O) method dynamically tracks the optimal regenerative voltage point with a 200 Hz update rate. Compared to conventional fixed-voltage regenerative schemes, the MPPT algorithm delivers significantly greater efficiency gains under partial-load conditions (30%–70% of rated load). The perturbation step size adapts automatically: 0.5V under steady-state conditions, increasing to 2V during sudden load transients, with an MPPT tracking response time of ≤50 ms.
Measured V2.0 Regenerative Efficiency by Load Rate
| Load Rate | Regenerative Efficiency (V2.0) | Regenerative Efficiency (Fixed-Voltage) |
|---|---|---|
| 30% | 91.2% | 87.5% |
| 50% | 93.8% | 90.1% |
| 70% | 95.1% | 92.3% |
| 100% | 95.8% | 94.2% |
| Load Factor | V1.0regenerative efficiency | V2.0regenerative efficiency(Without MPPT) | V2.0regenerative efficiency(Including MPPT) |
|---|---|---|---|
| 10%Load(4.5kW) | 6% | 11% | 14% |
| 30%Load(13.5kW) | 14% | 22% | 28% |
| 50%Load(22.5kW) | 18% | 28% | 33% |
| 70%Load(31.5kW) | 20% | 32% | 35% |
| 100%Load(45kW) | 22% | 34% | 35% |
Data source: Kelude Heavy Industry Energy Feedback System Test Laboratory, test platform KL-ERB-V2.0-Demo (April 2026). Test conditions: DC bus voltage 600VDC, grid voltage 380VAC/50Hz, ambient temperature 25°C. Regenerative efficiency = regenerative active power / DC-side input power × 100%. The MPPT algorithm delivers the most significant efficiency gains in the 30%–70% load range.
V2.0 Core Technology Upgrade: Intelligent Energy Management
The V2.0 intelligent energy management strategy supports automatic switching among three regenerative modes:
①Grid-Feedback Priority — When the workshop grid load is stable, recovered energy is fed back to the 380V grid first, filtered through an LCL filter (L=0.5mH, C=10μF) to remove high-order harmonics before grid connection, with THD ≤ 3% (compliant with IEC 61000-3-12 Class A limits);
②Supercapacitor Energy Storage — When grid fluctuations are significant or during peak electricity pricing periods (typically 10:00–12:00 and 18:00–20:00), energy is stored in the KL-SCM-10 supercapacitor module (rated voltage 800VDC, capacitance 14F, usable energy storage 10kWh, peak power 150kW/3s) for release during rapid crane starts and heavy-load acceleration;
③Assisted Braking Coordination — Under emergency braking conditions (deceleration ≥ 1.5m/s²), energy is prioritized to the auxiliary braking resistor cabinet (KL-ABR-30, 30kW/3.9Ω), working in tandem with the mechanical brake to reduce braking distance by approximately 15%–20%.
The system automatically selects the optimal strategy based on real-time electricity price signals from the factory Energy Management System (EMS) and grid conditions. In deployed projects, the intelligent energy management strategy delivers an additional 8%–12% improvement in overall energy-saving effect compared to grid-feedback-only solutions.
IEC 61000-3-12:2011 Harmonic Current Limits (Class A Equipment, I_sc/I_pe=250) vs. V2.0 Measured Values
| harmonic Cyclesn | IECLimit Value(A) | V1.0Measured(A) | V2.0Measured(A) | Assessment |
|---|---|---|---|---|
| 3Times | 2.30 | 1.85 | 0.92 | |
| 5Times | 1.14 | 1.42 | 0.68 | |
| 7Times | 0.77 | 0.98 | 0.51 | |
| 9Times | 0.40 | 0.58 | 0.29 | |
| 11Times | 0.33 | 0.41 | 0.22 | |
| THDtotal harmonic distortion | — | 5.2% | 2.8% |
Data source: IEC 61000-3-12:2011 Table 1 (Class A equipment, short-circuit ratio I_sc/I_pe = 250 limit). Measured data collected from the Kelude KL-ERB-V2.0 prototype test certificate (April 2026, test no. TS-ERB-2026-004) using a Fluke 435 II power quality analyzer under full-load 45 kW regenerative braking conditions. Note: The IEC table's 5th harmonic limit I_5 = 1.14 A is calculated for I_pe = 16 A/phase; actual limits scale per the standard's formula.
System Composition & Installation
The regenerative braking system consists of four core components:
The system is compatible with Siemens G120/S120 series (PM240/PM340 power modules), ABB ACS880 series (R8i/R9i frames), and Inovance MD500 series (MD500T45GB) VFDs, connected via a common DC bus architecture. Installation & commissioning typically takes 2–3 days.
Economic Benefits: Real-World Deployment Case
Case study: four 32 t QD Type double-girder overhead cranes in the cast steel workshop of a machinery manufacturing facility, each retrofitted with the Kelude regenerative braking system V2.0 and in operation for 10 months. Key economic benefit data from the project:
| Indicator | Pre-deployment(2024Year Q2) | Post-deployment(2025Year Q2) | Change |
|---|---|---|---|
| Total Energy Consumption(4Unit×Quarter) | 43.210kk Wh | 35.810kk Wh | 17.1% |
| Regenerated Energy | 0 | 7.410kk Wh | Newly Added |
| Comprehensiveregenerative efficiency(Measured) | — | 32.8% | Near Rated35% |
| Electricity Cost(Including Demand Charge) | ¥34.610k | ¥28.610k | ¥6.010k(17.3%) |
| CO₂Reduction Swept Volume(Based on0.5703t/MWh) | — | 42.2t | Current Quarter |
Data source: Kelude Heavy Industry Energy Feedback System project database, project no. KL-ERB-2024-009 (cast steel workshop of a machinery manufacturing enterprise). CO₂ emission factor references the Ministry of Ecology and Environment's 2023 national average grid emission factor of 0.5703 tCO₂/MWh. Electricity consumption data was provided by the client's Energy Management System (EMS) and confirmed by both parties.
Payback Analysis for the Energy Feedback System
| Item | Value | Remarks |
|---|---|---|
| Total System Investment | ¥52.010k | 4Unit×¥1310k/Unit(Including Installation & Commissioning) |
| Quarterly Electricity Savings | ¥6.010k | Electricity Tariff0.80RMB/k Wh |
| Annualized Electricity Savings | ¥24.010k | ×4Quarter |
| Staticpayback period | Approx.26Months | ¥52.0 ÷ ¥24.0/Year≈2.17Year |
| equipment design life | 10Year | Si CDevice Lifetime＞20Year(@T_j≤150°C) |
CO₂ reduction calculation basis: 74,000 kWh/quarter × 0.5703 tCO₂/MWh = 42.2 tCO₂/quarter. Based on an annual recovered energy of 284,000 kWh, the yearly reduction is approximately 162 tCO₂.
Technical Parameter Comparison Table
| Comparison Item | V1.0 | V2.0 |
|---|---|---|
| Power Device | Si-based IGBT(IKW75N60T) | Si C MOSFET(C3M0075120K×6) |
| Typical Switching Frequency | 4kHz | 16kHz |
| Full loadregenerative efficiency(45kW) | 22% | 35% |
| 50%Loadregenerative efficiency | 18% | 33% |
| total harmonic distortion THD | 5.2% | 2.8% |
| MPPTTracking | Without(Fixing Voltage Regeneration) | Perturb and Observe (P& O) Method P& O,200Hz |
| supercapacitor energy storage | Optional | Standard KL-SCM-10(10kWh/Set) |
| Annual Energy Savings(4Unit32t) | — | 28.410kk Wh |
| Year CO₂Reduction Swept Volume | — | ~162t |
| Gridharmonic Standard | Non-compliant IEC Class A | Non-compliant IEC 61000-3-12 Class A |
| deployed projects Cycles/overhead crane Cycles | — | 23Enterprises/86Unit |
| Warranty Period | 2Year | 3Year |
More related content: Crane VFD Speed Control System Selection & Commissioning: G120/ACS880/ATV930 Engineering Comparison, Crane Intelligent Energy-Saving System: Regenerative Braking and Supercapacitor Energy Storage Solutions
Frequently Asked Questions
Q: Which VFD brands are compatible with the V2.0 regenerative braking system?
A: The V2.0 system uses a standard common DC bus architecture and is compatible with VFDs from all major brands. Among the 86 overhead cranes already deployed: 47 units use Siemens G120/S120 series (PM240/PM340 power modules), 22 use ABB ACS880 series (R8i/R9i frames), 14 use Inovance MD500 series, and 3 use Schneider ATV930 series. For older cranes that still use rotor series resistance speed control, the VFD retrofit must be completed before the regenerative unit can be added. Kelude offers a one-stop upgrade service covering both the VFD retrofit and the regenerative system installation.
Q: Does the lifting height affect the energy recovery efficiency of the regenerative braking system?
A: Recovery efficiency is primarily determined by the load factor and lowering speed, with lifting height having a minimal impact. The highest efficiency (approximately 35% in field measurements) is achieved during full-load lowering at constant speed. When lowering with no-load or light load, efficiency drops to 14%–20% (see the efficiency data table above). Lifting height mainly affects the absolute amount of energy recovered per cycle (higher lifts recover more energy), but it does not change the efficiency percentage. The system operates effectively at lifting heights of 3 m (10 ft) or more.
Q: What are the power grid quality requirements for the system?
A: The regenerative system requires the connected grid to maintain voltage fluctuation within ±10%, frequency fluctuation within ±1%, and three-phase unbalance within 5% (per GB/T 15543-2008 standard). For sites where grid quality does not meet these requirements, we recommend using supercapacitor energy storage mode or routing the recovered energy to auxiliary braking instead. Kelude provides grid quality assessment services using a Fluke 435 II power quality analyzer, with a detailed inspection report issued to ensure safe and reliable operation of the regenerative system.
Q: How do V1.0 users upgrade to V2.0?
A: Upgrading from V1.0 to V2.0 requires replacing the regenerative unit (from silicon-based IGBT modules to the KL-ERU-V2.0 with SiC MOSFETs) and the controller (from KL-ERC-V1.0 to KL-ERC-V2.0 with MPPT algorithm). The existing LCL filter, DC bus, and supercapacitor modules are retained. The upgrade cost is approximately 40%–50% of a new system (roughly ¥50,000–65,000 / about $7,400–$9,600 per unit), and installation takes about one day. Of the 27 companies with V1.0 systems deployed, 11 have already completed the upgrade.
