Brushless DC motors (BLDC) — BLE2, BMU & BLV

A brushless motor has no brushes or commutator to switch the current. Instead, Hall-effect ICs in the stator report rotor position to the driver, and the driver's transistors energise the windings in sequence. The same Hall signals are counted as speed feedback, so the driver knows the real shaft speed and adjusts the voltage to hold it — this is what Oriental Motor means by speed regulation of ±0.2%.

The practical result is a speed-torque curve that stays flat from 80 r/min to around 3000 r/min, with a short-time torque reserve above that for starting and acceleration. An AC motor on a VFD, by contrast, runs open loop: when load rises, slip increases and speed falls. On a conveyor feeding a filler, labeller or printer, that difference shows up directly as product spacing and print position.

• Speed set on the driver (dial, keys), by external potentiometer, by 0–10 VDC or by software — no separate VFD
• Flat rated torque across the speed range, so a lower gear ratio can often be used
• Speed stays within ±0.2% as load, supply voltage and temperature change (digital setting)
• No brush wear, sparks or carbon dust; maintenance is limited to bearings and gearhead

Start with the power supply. If the machine runs from single-phase 230 VAC or three-phase 415/230 V control transformers, choose from the AC-input BMU and BLE2 series. If it runs from a battery or a 24/48 VDC bus — AGVs, AMRs, trolleys, mobile inspection units — choose the BLV Series R Type (or BLH/BLS for small 24 V drives).

Between BMU and BLE2, the motors and gearheads are shared; the difference is the driver. BMU is the one to choose when an operator simply needs to dial in a speed, perhaps with four preset speeds, and read the load factor. BLE2 suits machines where the PLC switches between many speeds, where you need torque limiting to protect a jam-prone mechanism, a simple holding torque at standstill, or an electromagnetic brake for a vertical axis.

Then size the output. Work out the torque at the gearhead output shaft and the required speed, choose a gear ratio that puts the motor between roughly 1000 and 3000 r/min for the normal operating point, and check permissible torque, overhung load and duty. Send us the load details and we will do the calculation.

• BMU: simple dial speed setting, 4 speeds, ideal for stand-alone conveyors and operator-adjusted machines
• BLE2: up to 16 speeds, torque limit, holding torque, brake types, PC software for set-up and monitoring
• BX II: when you need encoder feedback and very low speed operation down to 2 r/min
• BLV R Type: battery or DC supply, Modbus RTU/CANopen networking, AGV-focused functions
• Need positioning rather than speed control? Look at AZ Series closed loop steppers or servo motors instead

Oriental Motor's published data puts the power consumption of a 90 W brushless motor about 26% below that of an inverter-controlled three-phase induction motor doing the same job. Their 60 W comparison, based on 12 hours a day for 300 days a year, shows an AC motor using 439.2 kWh a year against 273.6 kWh for a BMU brushless motor — a saving of 165.6 kWh per drive, per year. On a line with twenty or thirty small conveyor and feeder drives running two shifts, that adds up.

The efficiency gain comes from the permanent-magnet rotor: there is no rotor current and therefore no rotor copper loss, and the motor does not need to be oversized to cover slip and low-speed torque drop. BMU motor-and-driver efficiency is published at 86.0% for 200 W and 87.0% for 400 W, which Oriental Motor states exceeds the IE4 class value at those outputs.

A VFD still has its place. For drives above a few kilowatts, for existing motors that are already installed, or where a rugged standard induction motor is required, a VFD is usually the more economical choice. The BLDC package wins below 400 W, where it is smaller, holds speed more tightly and needs no motor parameter set-up.

• Speed range 80–4000 r/min (50:1) vs a typical 200–2400 r/min (12:1) for an inverter-driven three-phase induction motor in Oriental Motor's comparison
• 120 W BMU motor: 1.2 kg vs 3.2 kg for a 90 W AC motor on the same 90 mm frame
• One matched motor-driver package instead of motor + VFD + parameter set-up

Most brushless applications need the motor's 80–4000 r/min brought down to a useful output speed with more torque, and the gearhead choice decides how the drive fits the machine. The parallel shaft (GFV) gearhead is the standard choice and the most economical; ratios run from 5:1 to 200:1 with a rated life of 10,000 hours.

The right-angle hollow shaft (JH) gearhead slides directly onto the driven shaft and turns the motor through 90°, so there is no coupling, no alignment job and far less protrusion from the side of a conveyor. The hollow-shaft flat (FR) gearhead does the same in line with the shaft, which suits narrow machines and AGV wheel modules. Foot-mount (JB) gearheads bolt down like a conventional gear motor for high-torque drives.

• Tight space beside a conveyor: right-angle hollow shaft (JH)
• Wet or wash-down areas: IP67 type, stainless steel shaft, H1 food-grade grease
• Heavy loads with base mounting: foot mount (JB)
• Always check permissible torque and overhung load at the output shaft for the chosen ratio

Battery-powered vehicles are where the BLV Series R Type earns its place. The driver accepts a wide input range (15–55 VDC) so it keeps running as the battery discharges, and it weighs about 0.12 kg in a 65 × 75 × 29 mm package, roughly 80% smaller than Oriental Motor's previous driver. That frees space and weight for battery capacity or payload.

The R Type adds functions aimed at vehicles: speed control down to 1 r/min for smooth docking, automatic torque limiting (ATL) to prevent a stall on overload, electrical load holding at standstill, electromagnetic brake types for ramps, Safe Torque Off, and Modbus RTU or CANopen so the vehicle controller can command both drive wheels and a top conveyor over one network. Hollow-shaft flat gearheads and flange drive adapters make compact wheel modules possible.

A brushed DC motor is simple and cheap: it commutates itself mechanically and its speed can be varied just by changing the voltage. The trade-off is brush and commutator wear, carbon dust, sparking and electrical noise, which make it a poor fit for continuous-duty industrial machines, clean rooms and food areas.

A brushless motor needs a driver, which raises the initial cost, but it has no wearing electrical parts, runs quieter, is more efficient and holds speed accurately under changing load. For conveyors, AGVs and machines that run a full shift every day, the longer life and lower maintenance usually pay back the difference quickly.