What are the main problems with electric motors/drive systems?

What are the main problems with electric motors/drive systems?

Different kinds of motors are going to present different issues. If we think about some of the issues that could potentially crop up with a motor, there could be any number of things, from general wear and tear to electrical failures, or other more specific faults. Let's take a closer look at some potential problems you could encounter with electric motors.  

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Motor temperature can either be measured directly or derived from parameters in the control system.  If such a system is on board, the motor can be switched off or de-rated in power. If not, it gets too hot and multiple failures can occur.

This can be induced from outside the motor or by the motor itself. This can lead to mechanical failures.  

Winding failure
Essentially a short between wires. The insulation of the magnetic wire has slight imperfections when it's produced. The winding and assembly process stresses the wire and the insulation on the outside. Even if checked at the end of the production line, the degradation or breakdown of the isolation material over time can be accelerated by temperature profiles, duty cycles, moisture and many more factors. The insulation is 'aging' and can ultimately fail, resulting in a short.

DC motor capacitors
DC motors use big capacitors to transform AC current from a plug to DC current for the motor. These capacitors can wear over time and eventually blow up, depending on the stress they have experienced.

Electromagnetic Compatibility (EMC)
Electric motors can emit electromagnetic waves, because their function relies on powerful magnetic fields that are rotating. The switching devices do their bit as well. The motor's controllers can also be impacted by the EMC of other devices.

Switching devices in controllers
(Typically, MOSFETs or IGBTs) can fail, due to power surges on the line or water ingress, for example.  

Insect infiltration can cause all sorts of issues, including mechanical wear, electronic failures, noise, etc. Spiders and bugs are classic examples, also rodents and birds can be problematic.

Bearings can be an issue, in fact, most motor failures are bearing related. The higher the speed, the trickier it is to select the right bearing. Ball bearings don't like water and dirt, while glide bearings don't like dirt and radial forces or shocks of any kind.

Power surges
Surges on the power network and wrong control without power limitations can demagnetize permanent magnets.

Water ingress
The switching devices inside the motor controller (Mostly MOSFETs or IGBTs) can fail due to water ingress.  

A current spike in the motor windings could occur from a failure in the electronics or software. This could result in demagnetization of the magnets.  

Mechanical friction
Brushes - the electric contact elements found in brushed motors, are prone to wearing out due to mechanical friction.  

Capacitor wear
The controls of AC motors are not complex. Degradation of the capacitor over time can cause it to blow and a replacement will be required.  

Environmental wear
Many types of electronics need to be protected from the elements and the environments in which they operate. Insect infiltration, water, dust and dirt ingress can all lead to failure. Extreme heat or cold can also damage the controller components. Each component has a specific rating which needs to be selected for its requirements.  

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As with any kind of electrical device, there is always the risk of problems, malfunction or failure. By selecting the right materials and components, carrying out excessive simulation and testing, experience and final product testing, these risks can be mitigated as much as possible. From a user point of view, following the manufacturer's guidelines on correct usage, regular maintenance and checks also helps to mitigate any potential issues, along with providing optimum performance and extending the lifetime of the motor.


Rob Keating

Rob is a content creator and copywriter for Fisher & Paykel Technologies. His work includes the Knowledge Hub, email, website and social media copy, along with customer communications.
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October 10, 2022
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