{"id":3627,"date":"2026-10-29T16:23:43","date_gmt":"2026-10-29T08:23:43","guid":{"rendered":"http:\/\/www.hesperuswebdesign.com\/blog\/?p=3627"},"modified":"2026-10-29T16:23:43","modified_gmt":"2026-10-29T08:23:43","slug":"how-to-start-a-permanent-magnet-synchronous-motor-441c-fe7ed2","status":"publish","type":"post","link":"http:\/\/www.hesperuswebdesign.com\/blog\/2026\/10\/29\/how-to-start-a-permanent-magnet-synchronous-motor-441c-fe7ed2\/","title":{"rendered":"How to start a permanent magnet synchronous motor?"},"content":{"rendered":"

Hey everyone, let\u2019s cut to the chase\u2014if you\u2019ve ever stared at a permanent magnet synchronous motor (PMSM) control panel like it\u2019s a foreign language, you\u2019re not alone. I\u2019m the team lead over at our PMSM supply shop, and over the past 7 years, I\u2019ve walked new maintenance techs, small factory owners, and even hobbyists through starting these things a hundred times. Yeah, they\u2019re way more efficient than their induction cousins, but skip a step here or misread a sensor there, and you\u2019ll be staring at a dead motor (or worse, a panicked team) before you can say \u201crare-earth magnet.\u201d This post isn\u2019t some stuffy engineering manual\u2014it\u2019s the real, no-BS playbook I\u2019ve used day in and day out, plus some pro tips I only pass on to people who actually need to get their lines running. Permanent Magnet Synchronous Motor<\/a><\/p>\n

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First off, let\u2019s nail down what a PMSM actually relies on, because starting it is 90% setting up for success before you even hit that start button. Unlike induction motors, which \u201cinduce\u201d their own rotor magnetic field, PMSMs have permanent magnets glued or secured right in the rotor. That means they\u2019re way more precise with speed and torque\u2014perfect for conveyor systems, electric forklifts, or even those big HVAC blowers you see in commercial buildings. But that precision only works if you get two things right first: rotor position feedback and the inverter\u2019s output. Mess up either, and you\u2019re looking at \u201ccogging\u201d (that jerky, not-quite-moving spin) or even backfeeding power that fries your inverter.<\/p>\n

Before we get to the step-by-step, let\u2019s do a quick pre-start check that takes 5 minutes tops\u2014don\u2019t skip this. I\u2019ve had a client call me at 7 a.m. last month, screaming their motor wouldn\u2019t start, only to find a tech had left the protective cover off the terminal box, and a stray wrench nicked a power cable overnight. Here\u2019s my go-to checklist: First, grab your multimeter (you don\u2019t need a fancy lab one\u2014just a basic digital model works) and check the DC bus voltage. That\u2019s the big cap bank sitting in the inverter cabinet. If it\u2019s way lower than rated (like, our 48V PMSMs need 52-56V DC to start), you\u2019ve got a loose connection or a dead capacitor charging. Next, check the phase wires between the inverter and motor\u2014should read roughly the same resistance on all three (like, within 10% of each other). If one\u2019s way higher, you\u2019ve got a broken wire or a corroded terminal. Last, do a quick visual of the motor itself: spin the rotor by hand (make sure power is OFF, duh) \u2014 it should spin smooth, no grinding or scraping. If it catches, you\u2019ve got a bearing issue, not a starting problem, and we can fix that before you waste 20 minutes messing with controls.<\/p>\n

Okay, the main event\u2014starting the PMSM. I split this into two modes because, trust me, not all starts are the same. If you\u2019re doing a regular, low-load start (like a conveyor that\u2019s empty), go with sensor-based vector control\u2014it\u2019s what our factory sets as default for 90% of orders, and it\u2019s the most reliable for day-to-day use. If you\u2019re cranking a heavy load (like a fully loaded forklift or a packaging line with 10 boxes stacked), use sensorless vector control with a low-speed pre-excitation step, but hold up\u2014more on that later. Let\u2019s start with the regular sensor-based start, since that\u2019s what most folks will deal with.<\/p>\n

First, make sure all the auxiliary power is on. The inverter, the PLC, any encoder cables (that\u2019s the thing that tells the motor where the rotor is\u2014super important), all should be powered up and communicating. If you get an error code here (most common ones are \u201cencoder comm loss\u201d or \u201cbus undervoltage\u201d), just go back to your pre-start check\u20149 times out of 10, it\u2019s a loose encoder connector. Next, zero the reference position. This is the big one I see new techs mess up all the time. The encoder doesn\u2019t know where the rotor\u2019s North pole is unless you tell it. Most modern inverters (ours included) have an auto-alignment routine, so you don\u2019t have to do it manually. Here\u2019s how we run it: Hold the start button for 3 seconds, or navigate the inverter\u2019s little touchscreen (or keypad, if it\u2019s the older model) to find the \u201cRotor Alignment\u201d function, and hit enter. The motor will make a small, quiet click and twist about 10 degrees\u2014don\u2019t panic, that\u2019s just it locking onto the magnet. That\u2019s normal. If it beeps and gives an error here, turn off the inverter, spin the rotor by hand a quarter turn, and try again. I once had a client who skipped this step and tried to start their 10HP PMSM, and it locked up so hard she had to call a mechanic to break it free. Oops.<\/p>\n

Now, set your speed reference. Most systems have two ways: analog (a 0-10V signal, usually from a PLC or potentiometer) or digital (an HMI input or a predefined setpoint). Don\u2019t jump straight to full speed\u2014start at 25-30% of your rated speed first. Why? This lets you check for cogging. If the motor jerks and doesn\u2019t spin, shut it off immediately. That\u2019s either a bad alignment or a load that\u2019s too high for the start mode. Once it spins smooth at low speed, you can ramp up to your target speed at about 10% per second. No fast ramps\u2014PMSMs hate that, and it\u2019s a quick way to wear down the bearings or trip overcurrent protection. Once you hit your set speed, hold it for 30 seconds. If there are no error codes, you\u2019re good to go. Most of our clients leave this part alone because we pre-program the inverter, but it\u2019s good to know if you ever need to adjust it.<\/p>\n

Now, that heavy-load start I mentioned earlier\u2014this is where sensorless mode comes in. Sensorless is great because you don\u2019t need an encoder, so it\u2019s cheaper, but it doesn\u2019t have that exact rotor position feedback. For loads over 70% of the motor\u2019s torque rating, sensorless can fail if you skip the pre-excitation step. Here\u2019s how we do that: First, set the speed reference to 5-10% (way lower than the regular start). Then, hold the start button for 5 seconds instead of 3. The inverter will send a small DC current to the stator for a second, \u201cwaking up\u201d the permanent magnets so it can get a rough position. Then it\u2019ll start ramping up slow. This avoids that dead spot where the rotor just sits there because it\u2019s aligned wrong. I used to skip this when I was new, and I ruined two PMSMs before my boss sat me down and told me I was being an idiot. Don\u2019t be that guy.<\/p>\n

Wait, let\u2019s talk about common mistakes that\u2019ll get you in trouble. First, overloading at start. A lot of folks think, \u201cMy motor is 20HP, so it can start my 20HP load\u201d but PMSMs only have so much starting torque. If you\u2019re starting a full load, even a big PMSM needs that pre-excitation step. Second, ignoring error codes. I know, it\u2019s tempting to just hit reset and keep going, but that error code is telling you something. Last month, a local bakery\u2019s motor kept throwing an overcurrent error. They hit reset three times, and eventually the inverter tripped permanent. When I checked, the conveyor belt was jammed with dough, so the motor was pulling way more current than it should. If they\u2019d checked the error code first, they would\u2019ve fixed the jam in 2 minutes instead of ordering a new inverter.<\/p>\n

Also, a quick note on safety\u2014always, always make sure the motor is isolated from the load before doing a test start. If you start the motor with the conveyor belt connected and something\u2019s wrong, you\u2019ve got a runaway belt, which is a hazard. Last thing: after starting, listen to it. A healthy PMSM should make a quiet, steady hum\u2014no grinding, no high-pitched whine, no sudden changes in sound. If it does, shut it down and check that pre-start checklist again.<\/p>\n

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At the end of the day, starting a PMSM isn\u2019t rocket science, but it\u2019s not just plug and play either. It\u2019s about nailing that pre-start check, getting the rotor aligned right, and picking the right start mode for your load. If you\u2019re messing with these regularly, get to know your motor\u2019s specs\u2014our team can hook you up with a free spec sheet if you need it, no pressure. If you\u2019ve got a PMSM that won\u2019t start, or you\u2019re looking to upgrade to a more efficient unit, hit us up\u2014we don\u2019t do sales fluff, just honest advice and parts that actually work.<\/p>\n

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Explosion Proof Motor<\/a> References<\/p>\n

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  1. Bose, Bimal K. "Modern Power Electronics and AC Drives." Prentice Hall, 2002.<\/li>\n
  2. Permanent Magnet Synchronous Motor Application and Installation Guide. Magnetek Industrial Automation, 2021.<\/li>\n
  3. "Rotor Position Alignment for Sensor-Based PMSMs." IEEE Transactions on Industrial Electronics, vol. 65, no. 11, 2018, pp. 8501-8510.<\/li>\n<\/ol>\n
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    Xi\u2019an Simo Motor Co., Ltd.<\/a>
    Xi\u2019an Simo Motor Co., Ltd. is well-known as one of the leading permanent magnet synchronous motor manufacturers and suppliers in China. Please feel free to buy high-grade permanent magnet synchronous motor in stock here and get quotation from our factory. All customized products are with high quality and low price.
    Address: No. 159 Mingguang Road Economic and Technological Development Zone, Xi’an, Shaanxi Province, China
    E-mail: mkt-sales@simo.com.cn
    WebSite:     https:\/\/www.simomotor.com.cn\/<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

    Hey everyone, let\u2019s cut to the chase\u2014if you\u2019ve ever stared at a permanent magnet synchronous motor … How to start a permanent magnet synchronous motor?<\/span>Read more<\/a><\/p>\n","protected":false},"author":18,"featured_media":3627,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[3590],"class_list":["post-3627","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industry","tag-permanent-magnet-synchronous-motor-423b-fec3d6"],"_links":{"self":[{"href":"http:\/\/www.hesperuswebdesign.com\/blog\/wp-json\/wp\/v2\/posts\/3627","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.hesperuswebdesign.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.hesperuswebdesign.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.hesperuswebdesign.com\/blog\/wp-json\/wp\/v2\/users\/18"}],"replies":[{"embeddable":true,"href":"http:\/\/www.hesperuswebdesign.com\/blog\/wp-json\/wp\/v2\/comments?post=3627"}],"version-history":[{"count":0,"href":"http:\/\/www.hesperuswebdesign.com\/blog\/wp-json\/wp\/v2\/posts\/3627\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.hesperuswebdesign.com\/blog\/wp-json\/wp\/v2\/posts\/3627"}],"wp:attachment":[{"href":"http:\/\/www.hesperuswebdesign.com\/blog\/wp-json\/wp\/v2\/media?parent=3627"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.hesperuswebdesign.com\/blog\/wp-json\/wp\/v2\/categories?post=3627"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.hesperuswebdesign.com\/blog\/wp-json\/wp\/v2\/tags?post=3627"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}