Spin Your Motor in 45 Seconds! 10 Reasons to Use Rotate-it! Motor Control Solution Kits
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The goal of any engineer designing a 3-phase inverter for an AC Brushless motor is to quickly get a running solution, tuned to his specific motor. An ideal design tool fulfilling this dream would enable automatic measurement of the motor parameters; ensure tuning of the system power stage; calibrate the coefficients of the Proportional/Integral current regulation block and guarantee a safe and reliable start-up process. Renesas are now offering such a dream tool as an enhancement to their existing RL78/G14, RX220, RX62T/RX63T Motor Control Reference platforms currently available. The enhancements to the Motor Control kits enable design engineers to plug-in and tune their own motor within a few minutes, allowing speedy and efficient system optimisation.
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Spin Your Motor in 45 Seconds! 10 Reasons to Use Rotate-it! Motor Control Solution Kits
- 1. Industrial & Communications Business Group Renesas Electronics Europe Rev. 1.00 © 2014 Renesas Electronics Europe. All rights reserved. Spin Your Motor in 45 Seconds! 10 Reasons to Use Rotate-it! Motor Control Solution Kits 1
- 2. © 2014 Renesas Electronics Europe. All rights reserved. Drive Any Permanent Magnet AC Motor Supported 3-Phase Motors: • AC or AC/DC Brushless • Surface or interior • In-Runner & out-runner 2
- 3. © 2014 Renesas Electronics Europe. All rights reserved. 3 Everything to Spin Your Motor in 45 Seconds Proven Motor Control Complete Hardware Platform Royalty-Free Source Code Platform & Power Supply Reference Design Full Safety Certification All this for less than 200 Euros! Embedded Auto-Tune Software Schematic & PCB Layout Review Brake System Testing Expert Partner Services
- 4. © 2014 Renesas Electronics Europe. All rights reserved. Auto-Tune Software Embedded in the MCU! 4 MCU takes away any trial and error! Results can be manually refined & optimised… No oscilloscope or system current step needed
- 5. © 2014 Renesas Electronics Europe. All rights reserved. Automatic Motor Parameter Identification 5 Just a couple of mouse clicks Parameters identified by 3-phase inverter itself No need for any dev tools or oscilloscope!
- 6. © 2014 Renesas Electronics Europe. All rights reserved. Proven Royalty-Free Source Code Motor Control Algorithms Full software library in the box Free of charge No royalties or licenses for use Already in mass production use Field oriented control Sensorless 6
- 7. © 2014 Renesas Electronics Europe. All rights reserved. 7 Full Platform & Power Supply Reference Design Fully brake-tested 1.5KW power supply design
- 8. © 2014 Renesas Electronics Europe. All rights reserved. 8 Complete Confidendence in Safe Operation IEC 60730 Safety compliance Outstanding Noise immunity Automatic shutdown A/D converter self-diagnosis Running Overload detection
- 9. © 2014 Renesas Electronics Europe. All rights reserved. 9 Intuitive PC GUI Install then spin your motor within one minute!
- 10. © 2014 Renesas Electronics Europe. All rights reserved. 10 Scalable Microcontroller Configurations Rotate it! for RX111 - Optimised system response - Drive a single motor Rotate it! for RX62T - Fast system response - Drive two motors Rotate it! for RX220 - Medium system response - Drive a single motor
- 11. © 2014 Renesas Electronics Europe. All rights reserved. Expert Services to Secure Your Schedule 11 Software royalty-free On-site calibration & design support Schematics & PCB layout reviewed Renesas lab with braking system Compiler unlimited for 60 days
- 12. © 2014 Renesas Electronics Europe. All rights reserved. Find Out More! 12 www.renesas.eu/motor RenesasPresents http://youtube.com/RenesasPresents @Renesas_Europe https://twitter.com/Renesas_Europe Renesas Europe http://www.facebook.com/RenesasEurope Renesas Europe https://plus.google.com/+RenesasEu/posts
- 13. © 2014 Renesas Electronics Europe. All rights reserved. Renesas Electronics Europe © 2014 Renesas Electronics Europe. All rights reserved.
Notes de l'éditeur
- Welcome Ladies & gentleman to the Session co-presented by Renesas and BFG Engineering, my name is Vincent Mignard, responsible person for Motor Control solution in Europe within Renesas.Presenter: Andrea Ghirardello & Vincent Mignard [BFG Engineering & Renesas]Date: Thursday the 10th of October 2013One sentence to recap the main idea “Engineers have to struggle a lot to incorporate new motors & electronics in their equipment, Renesas auto-tuning solution + Ref. platform strongly reduce their development times & effort.”Title: Tune & Calibrate Your Permanent Magnet Motor in a few Mouse-Clicks Abstract: The dream of any engineer designing a 3-phase inverter for an AC Brushless motor is to quickly get a running solution, tuned to his specific motor. An ideal design tool fulfilling this dream would enable automatic measurement of the motor parameters; ensure tuning of the system power stage; calibrate the coefficients of the Proportional/Integral current regulation block and guarantee a safe and reliable start-up process. Renesas are now offering such a dream tool as an enhancement to their existing RX62T Motor Control Reference currently available. The enhancements to the RX62T Motor Control Kit enable design engineers to plug-in and tune their own motor within a few minutes, allowing speedy and efficient system optimization.
- Let me introduce you Markus. He’s electronic engineer and responsible for the h/w and s/w design of the control of such industrial shutter.Reliability & Safety are key issues for him.The current design is using Universal motor… and his new task is to replace the current motor & electronics by a more efficient motor: a Permanent magnet one + an inverter.
- His new task is to design the electronic to drive new type or motors: 3-phase permanent magnet motor.But, how to drive such motors? Which controls to be used to reach the highest efficiency?Which type of electronics in terms of Microcontrollers, power stage, etc.?Markus has limited expertise in such motors, such electronics and the software supposed to drive it The deadline is in 2 months to present a working prototype driving the current shutter.
- Markus did a rough costs estimation of the developments, the timing and the resources needed….Furthermore, it will take time, efforts, money and resources to deliver a first prototype within two months.Today, Markus has limited resources, reduced team and bandwidth, limited money to invest, less time to Optimized… First schematics, PCB layout, tests, verification,PCBs mounting, tests, uploading first s/w.Markus has a very limited knowledge about the PMSM motor and inverter…
- To help Markus, BFG Engineering designed, developed and delivered inverter reference platforms driving AC permanent Magnet motors.The platform is based on the RX62T microcontroller, using Floating Point Unit, and running at 100MHz.The 32-bit architecture is perfect for such application.The Kit is delivered with source code.A single PCB is composed with the Microcontroller, the power stage and the sensing shunt used to manage sensorless control.To ensure the highest dynamics, the algorithm is running on the floating point unit to ensure Field oriented control of the AC Brushless motor.The PWM and the control loop are both running at 16KHz. The CPU load is about 40%.
- But Markus is scared as he needs to invest in expensive tool & equipment: Oscilloscope, current probes, brake system, isolation transformer, trace debugger, … Does he needs to invest a complete lab equipment…?
- No, the reference platform provided, first of all it USB isolated, so at this point no isolation transformer is needed.Furthermore, the PC GUI is able to display the Kp and Ki coefficients of the PI current responsible of the control of the current in the field Oriented Control algorithm.No expensive tools needed thanks to the enhanced PC GUI interface and embedded software into the Microcontroller.The phase, the current and the step response of the current PI coefficients are displayed automatically.
- What about the safety & reliability of such systems? Hardware, software ?How do I detect any failures like rotor lock? Over-voltage? Loss of phases? Running overload?I need to able to measure the temperature of the motor winding in a simple way and cheap way !What happen if the power stage is defect?Which fail safe mechanism are available?1o years of reliability is needed for my system…
- Microcontroller itself is extremely Robust. Langer EMV performed burst tests on the RX62T showing the best in-class noise immunity.Furthermore, the Port Output Enable is able to switch off the PWM signals in hardware in case of emergency or failure detected or over-current.Power stage failure detected in h/w and automatic shutdown of the PWM.Stator resistance measurement in real-time: detect any failures.Finally the IEC safety compliance is ensured by a set of routines: CPU check, clock check, RAM check and flash tests proven by VDE.
- I selected different PMAC motors that could be fine… What is the next steps… tuning all of them and performing tests…It will take me ages ! I want to test the robustness, efficiency, the dynamics over the speed range….I may spend a lot of time and effort to tweak the s/w to each motor…
- Current PI blocks has two coefficients: Kp and Ki that are tuned automaticallyThe Motor parameters are identified: the stator resistance, the synchronous inductance and the Permanent Magnet flux.Finally the oscilloscope window is used to visualize the phase and the currents in the motor.Even for my mum it’s becoming easy.
- Now Markus feels good ! It’s a happy man.Finally what is the costs of the kit?Is the source code available?How is the Bill Of Material?
- Markus spent only €30K, only one month and only one person !
- It seems that Markus met his tough deadline at a reasonable cost using Renesas Ref. Kit.
- Now, let me introduce you:Andrea Ghirardello from BFG Engineering, he’s an expert in inverter and motor control algorithms.He designed the embedded software of the platform using Renesas RX62T.He will give you more background regarding the methods used to perform auto-tuning & calibration automatically.
- The software algorithm designed is a Field Oriented Control sensorless software.Specific hidden parameters/coefficients are used to adapt the s/w to each motor.Let’s dive into the Proportional Integral Block dedicated to the current control of the motor. First of all let’s give a look to the software block scheme. We are talking about a sensor-less motor control algorithm for brushless permanent magnets synchronous motors. Sensor-less here means that we don’t use speed or position sensors to drive the motor. I imagine you are all familiar with such kind of motor control algorithms, but just to remind, the structure is the following: an external speed loop produces the torque reference, two internal current loops produce the voltage references, which are applied by the inverter. Using reference systems transformations, we work in a reference system in which the torque and flux controls are decoupled, so the torque reference become immediately a current reference, and also the flux reference becomes a current reference. In steady state they are both DC quantities. We don’t go in deep to see how the flux reference is calculated, we just observe that in an isotropic motor the best choice is 0. A great part of the algorithm consists in the reference systems transformations. In particular the transformation between the two-dimensional system reference linked to the stator and the two-dimensional system linked to the rotor (the first is standing, the second is usually rotating; the transformation is called PARK transform), requires the knowledge of the angular position of the rotor as regards the stator. This position is the position of the permanent magnets flux vector, and to know it a sensor-less system needs to performs some calculations based on the motor model. The control loops are performed using standard PI controls (GO ON). In particular, the PI controls which take care of regulate the currents need to be tuned, which means that we need to know the values of their gains (GO ON, pause, GO ON).
- What does it bring to use a Proportional Integral Controller? To control the current delivered to the motor and the motor torque.It’s a fundamental part of the motor control algorithm.The PI controller is designed to produce a composite output to compensate the error.The two terms are called: Proportional coefficients and Integral coefficientsOnly to remind, a “Proportional Integral” control is a system which allows us to obtain a quantity to follow our reference; for example we want that a certain current follows a specified waveform, and to do this we need to impose a certain voltage waveform. The PI is creating a voltage waveform in such a way that the resulting current is following the desired waveform (GO ON). This is obtained comparing the actual system output with the desired one, and building an opportune system input based on the error itself. The input to feed the system is composed by two terms, one proportional to the error, the second proportional to the integral of the error (the proportional term alone would not bring to zero error, since zero error would mean zero action). The coefficient to find are the two gains of the two actions, and obviously their value depend on the transfer function of the controlled system (GO ON).
- The motor model for a single phase is made with v(t) generated by the PI controller and one inductance & one resistance.In order to find out the Kp and Ki, the quotient L/R and 1/R need to be measured.In our case the controlled system can be seen as an RL circuit, in fact it is a phase of the motor (GO ON). The step response of this circuit is the one represented in the graph (GO ON). The classical synthesis of a PI controller is usually based on the desired steady state gain and the desired phase margin (Bode diagrams and so on), while the manually tuning method proceeds by attempts, till we find the desired answer to a step reference, from which we have indication regarding the stability and the pass-band of the control. Having in mind which kind of step response we would like to obtain from the closed loop system, and knowing the steady state gain and the time constant of the RL equivalent circuit, we can obtain the PI controller gains (GO ON).So, the automatic tuning procedure should simply (GO ON):
- apply a voltage step (GO ON);Take opportune measurements on the response (GO ON);Calculate the PI gains (GO ON).In this way we can approach the ideal tuning, which can be refined “by hand” (GO ON).
- The software algorithm designed is a Field Oriented Control sensorless software.Specific hidden parameters/coefficients are used to adapt the s/w to each motor.Let’s dive into the Phase Estimation Block which is using the motor model parameters: Stator resistance, synchronous inductance and the Permanent Magnet flux.Let’s come back to the control algorithm block scheme. The block which requires the knowledge of the motor model parameters is the flux position estimation (GO ON). Here there are different possibilities (estimators, observers and so on), and depending on which one is chosen more or less parameters are required. In our case (we have an estimator based on pure integration) we need the complete knowledge of the motor model, and this means the knowledge of the stator resistance Rs, the synchronous inductance Ls, and the permanent magnets flux amplitude Lambda (bemf constant) (GO ON).
- Vector form equations isSince we are still not “Field oriented”, the model we can use here is referred to the stator. In the equations which describe the model are present two derivatives, but in sinusoidal steady state they can be calculated and substituted, obtaining the final vector relation, which presents (GO ON) the unknown parameters. Let’s observe that if we impose a sinusoidal voltage at a certain frequency, and measure the obtained current, all the quantities in the equation are known, apart our coefficients (GO ON).So the estimation method is simply (GO ON): showing the three parameters of the motors that needs to be extracted & identified.
- Stimulate the motor with different voltage waveforms (GO ON);Take the measurements of the corresponding currents (GO ON);Then solve an algebraic system (GO ON).
- At this point the motor model is known and we can drive the motor.
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