AC Induction vs Inverter BLDC Motors: How to Compare Loaded Starting Performance

Even a motor that can start when an empty washer cannot always handle wet laundry. If an OEM is comparing AC induction and inverter BLDC drives, a more useful question than one replacing the words “say” would be whether each proposed system can meet the load at start, reach speed specified say 24% faster plus repeat (or reverse) that sequence within its electrical and thermal limits. Compare washing machine motor torque at the same mechanical reference point and under defined test conditions. A rated wattage or a load free demonstration is not enough to make up the decision.

By AC induction, we mean a base-level single-phase, mains fed washer motor here. BLDC is a brushless motor driven by the suitable inverter drive. Now with variable-speed drive and induction motors, but that’s another subject. Neither one of those labels, on its own, implies loaded starting potential. Not by themselves does either label make loaded starting ability

Define what the washer must start

Begin with the wash-type motion you want to make. Loading wet fabric into a front-loading drum is fundamentally different than moving an agitator through water and clothes. Those duties are not equivalent simply due to the same nominal laundry capacity. Before soliciting samples, record the washer architecture and water level (if applicable), fabric load, initial load distribution in column / row coordinates for grid type washers* as well as required direction of rotation.

Starting torque is how much rotation you start with. Rated torque refers to a defined operating point once the motor is running. In the book AC Motor Terminology Lookup, by Oriental Motor describes the difference. When developing washers both the initial motion and then acceleration are relevant too: a system could overcome static friction but never actually reach its commanded speed.

Choose a reference shaft. Whenever a belt or gearbox is applied in one of the proposals, compare delivered torque and speed at that driven load with those values from any second proposal also involving power delivery to that same driven mechanism. Include transmission losses and limits. One consequence of this is that comparing motor-shaft figures without the ratios can make a smaller motor look inadequate while output numbers change due to mechanical reductions.

Question supplier where torque was measured, is it a measurement value or calculated or controller estimated? So far you keep those labels on the evaluation report. Washer capacity number is an application guide, not a replacement for this.

Check the complete AC induction configuration

An AC docket ought to specify the particular motor winding, deliver voltage and frequency (and capacitor where relevant), switching scheme and allowed duty. Here are examples of products for automatic washing machines from the AC industry hazards induced motors range in Nanyang. The picture below shows what product category–it does not show a test result or fit to one washer.

Asks for start data of billing & measurement and cap state configuration If you measure a capacitor say C7, do not substitute it with some convenient lab component and then use that measurement as production verification. Measure the actual motor voltage at startup, as a pre-energization measurement could miss an upstream dip. Log the voltage found on the motor during starting (ideally you should measure this at a point after energization, as measuring before can miss a supply drop)

Let a first start be different from restart after operation. The winding temperature, residual motion and load position may differ. In the case of reversal during wash program, configure how long before to stop or dwell etc in next start. These other conditions are left to be answered in the event that one is successful on a cold start in just one direction. The successful cold start in one direction leaves so many of those other conditions unaddressed.

Check the BLDC motor together with its inverter

In our case BLDC washing machine motor is only one component of the Drive system. The controller, current limits, either position feedback or estimation method and accelerations also affect its initial behavior. Approve the motor and inverter together as a matched proposal not individually from separate catalog descriptions. Additionally, confirm the motor and inverter as a matched proposal rather than two independent approvals from catalogue descriptions

Startup can need an additional strategy since for a sensorless drive based on back electromotive force, the system does not have enough rotational feedback. Other feedbackorganization do not have this request. Ask which methodology the proposed system really applies, how it determines direction and where a failed start is flagged up. Not every BLDC controller uses the same sequence!

The programmed ramp may assist one load to come on in the available torque range, but must still complete its timing for wash as per the program. Raising the current limit costs more than one US dollar − The motor/inverter/wires and thus protection limits must remain in their contractual ranges. Nanyang has some drive control products that could begin discussion of what motor-controller scope is needed.

Before comparison testing, freeze the firmware and parameter version. If ramp or retry logic for suppliers changes from run to run, keep both versions and track which version produced each result. That way a difference thought to be motor technology may actually just be software. Sorry, but a change that seems like it should be down to the motor tech may actually end up being a software switch

Build a washing machine motor torque test matrix

Employ identical needed load-side movement and and also acceptance standards regarding both systems Every system will maintain its largely equivalent electrical arrangement. Forcing an inverter drive and a mains-fed motor to have the same internal circuit does not represent fair testing. Forcing an inverter drive and a mains-fed motor to use the same internal circuit is not fair testing

Do not wait till the time of testing, in advance set your pass criteria. Set target slowness and allowed starting are, what is the excess proclivity acceptihg on initial motion and does an autoretry get you closer to success. Record sample identity and repetition count Your quantities and limits should be pulled from the product specification across the development plan, NOT some generic checklist you found online.

Also, capture where we are now. BLDC phase current, DC-bus (inverter) and AC mains currents are the readings. To compare their peak values as if they were measuring the same thing creates a false ranking. Choose a defined mains measurement when analysing supply demand, and choose the relevant motor-side measurement when examining drive limits.

Testing needs to be done in a moderated engineering process. A jammed-load probe is distinctive from an ordinary loaded-start test and requires specified protection, length, and shut-down criteria. The testing capability of Nanyang is capable enough to help a discussion on evidence needed for the specific project; agree with supplier, actual test scope and report format.

Read the failure sequence before changing the motor

You diverge from the approach used on a switch to first event when it comes time for washer not starting. Did the motor keep still, move for a instant in wrong rotation, accelerated then stopped or had triggered protection before moving? Store the traces of voltage, current and speed for events related to that idioma We may have a final fault code, but it often explains the sequence only. The sole ordering of a final fault code may perhaps not describe the series

Inspecting an AC System: Confirm supply, capacitor, connections, mechanical resistance and switching sequence. Math system -> current limiting, feedback validitity ( note: thus be defined), : startup parameters fault handling for a BLDC system They both are still reliant on the mechanical assembly. A snug bearing, a mismatched gear should not be proof that an entire motor class is bad.

Alter one known condition at a time and rerun the relevant cases. After a correction is successful, perform the wider consensus matrix with that corrected configuration. Retain the failure so that production can understand which property or component mattered. I believe from sorting out successful and unsuccessful attempts, you would want to keep the failed result in record so that production team can identify what setting or component had an effect.

Questions from OEM teams

Does higher rated power mean higher motor starting torque?

No, nominal power is associated with a specific running condition. For any new starting capability, we need torque and drive information on the supply, controller or capacitor, mechanical load etc. Ask for necessary Initial Data and check both the Acceleration period as well as First movement. Simply adding a larger wattage label does not show an improved loaded start.

Is an inverter BLDC motor always better at starting a heavy load?

No. A properly sized BLDC system provides control of the start-up, but it is motor-, inverter- and setting-dependent within a load. A properly designed induction system can also do the trick. Use the same washer acceptance criteria to compare documented results rather than selecting a technology by its label.

Send a starting requirement that suppliers can evaluate

Prepare the washer arrangement, load-side movement, supply range and transmission points of interest on a helpful washing machine motor torque comparison individual warm-restart conditions acknowledgment measures up to October 2023. Include the proposed controller, or capacitor for each configuration and ask them to produce results spanning that unique combination. Talk to Nanyang Motor about the loaded-start requirement so that the proposed an AC induction or inverter BLDC system can be evaluated relative of what work it must perform.