F.A.Q

Frequently Asked Questions

Answering questions about our piezomotor technology and control drivers
We've organized all the questions from our customers into the following areas:

1. Control driver

2. PCBMotors

If the information you need for your project or application is not here, email our Support Team outlining your question and we'll get back to you with an answer as soon as we can.

1. Control Driver

Do I have to purchase the control driver from PCBMotor?

No, you don't need to purchase the driver from us. We're happy to provide you with the schematic, enabling you to make your own driver. But if you insist, we can of course supply you with the driver.

How does the control driver work?

The motor operates in resonance at approximately 40 kHz and is driven by a two-phase sinusoidal drive voltage of 100-200 Vrms. The angular difference between the phases is 90 degrees. Since the resonance is slightly dependent on the temperature of the PCB, the driver frequency control should take this into account.

Please see our development box which has a rich set of features for controlling the Motor.

 http://pcbmotor.com/test-eval-lab-kits-10/lab-kit-standard-103.html

Question: Can I track the drive frequency of the PCBMotor?

Answer: Yes. By measure the DC supply current to the motor driver. The motor resonance frequency is mostly determined by mechanical constants of the PCB-material and it is necessary to compensate for the change in resonance frequency for the best performance over temperature. For continuous operation the new tracking feature in our Development box version 4 is an effective way of setting the optimum frequency to compensate for the self-heating in the motor.

Question: What supply voltage do the driver need?

Answer: The driver for the PCBMotor is supplied with a 5V power supply, and the transformers in the driver circuit is stepping the voltage up from 5V to 100-200Vrms. The Vs supply for the transformer can be decreased down to approximately 3V to make the motor slow down. However, when the rotor is mounted on the stator a minimum drive voltage is required to overcome the static friction between the rotor and stator and start the motor turning.

Question: Can I drive several PCBMotors with the same driver?

Answer: Yes, 1 central driver can drive several motor positions. In fact the picture we are showing on the front at our webpage shows that 1 central driver is controlling 8 motor positions, one at the time, and this system can easily be expanded to a larger number of motor positions.

Question: Can the PCBMotor, control driver and my applications electronic be at the same PCB?

Answer: Yes. Both the PCBMotor, the driver electronic and your application can be on the same PCB if desired. See for example the picture we have on the front of the web page.

Question: What is this the cost of control driver for larger volume?

Answer: The basic component in the driver is the transformers which are needed for stepping up the drive voltage from 5V to 150V. In large volumes >100ku the transformer price will be app. 0,80 EUR each, and each driver needs two transformers. The price is not negotiated, so it might be possible to drive the cost lower. The remaining components for the driver will be at the price level at 0,8 EUR as well.

Estimated total component prices per driver will be app. 2,50 EUR for volume larger than 100Ku. This is based upon the present design for the driver components, and there is no NRE needed to achieve this price.

Question: Can the control driver be smaller?

Answer: Yes. However, if your application requires as little space as possible it could be considered to make an ASIC where some of the driver components are integrated into one I/C. NRE for make a ASIC will depend of the technology chosen, project complexity, timeframe etc, and therefore you should evaluate the cost with the benefit of having smaller driver electronics.

Question: Can I use smaller transformers?

Answer: The transformer in the driver output stage has two functions:

1.    Stepping up the voltage, hence the winding ratio of ca 1:40

2.    Providing an electrical resonance to match the mechanical resonance at 40kHz

As regards 1): Operating from a higher DC voltage than 5V will lower the number of windings on the secondary side and thereby the sectional Cu-area. However this will contrast with the requirements of 2) (see below). The trafo also has to be able to handle the required current for the piezos, but with the current trafo size there is ample margin – the trafo only gets lukewarm at full power.

As regards 2): The output stage is in electrical resonance at 40kHz with a Q of approximately 10. With the electrical resonance matched to the mechanical, this is a very power efficient way of driving the capacitive load of the piezo’s, which is ca 300pF/phase for a dual sided Ø30mm stator. This means that the inductance should be 50mH to match a Ø30mm stator or 150mH to match a Ø10mm stator. A core with Al=250nH and ca 450 windings on the secondary will give you 50mH, while you will need 775 windings to match the smaller stator.

So, the sectional Cu-area and the inductance are the limiting factors in the core design. Using wire with a diameter of 0.05mm and cores with Al=1000nH would both have a significant impact on the trafo size but the price would probably be way up.

Question: Can I use the control driver to step the motor?

Answer: Yes. The motor is not limited to a fixed number of steps. The motor can Start < 0.4ms and stop < 0.1 ms.  This equals a resolution > 20000 steps/rev @ 0.4ms/step. A heavier rotor than 5 gram will increase start and stop time.

Question: Can I control the position of the rotor?

Answer: Yes. A position sensor is required for precision. A relative position sensor can easily be implemented by a reflective photo detector on the PCB and a black/white marking on the lower side of the rotor. For higher precision an analogue sensor should be used.

Question: Is there EMC problems with the control driver?

Answer: No, EMC problem is not at severe as the frequency is quite low (160kHz divided to 40kHz for each winding) and since the stator is operating in near resonance, i.e. sine wave. We have done some EMC testing and with the present layout of the driver; it will need some additional decoupling and shielding to pass a standard EMC test. We believe this is doable, but have refrained herefrom since the driver ordinarily is rebuilt to our customers’ PCBs. The high voltage is in it self not a problem since all switching is occurring on the primary side.

2. PCBMotors

Question: What kind of applications is best suited for this technology?

Answer: There are countless possibilities where the PCBMotor can be used, some examples see list below:

• Medico
  –        Microscope focus
  –        Dosing equipment

• Instrumentation
  –        Dashboard pointers
  –        Positioning
  –        Laboratory equipment

• Telecom
  –        Filter tuning

• Audio and video
  –        Audio mixing equipment

• Factory automation and robotics
  –        Industrial machinery and equipment

• Aerospace and aviation

Question: Do PCBMotor build PCBMotors?

Answer: Yes. PCBMotor can design, and manufacture complete PCBMotors containing the stator, driver and positions sensor that’s fit your application. See Flow  in the top menu or follow this link

http://pcbmotor.com/information/4b-standard-flow-28/

Question: Can I build PCBMotor on my own?

Answer: Yes. PCBMotor can provide training enabling you to design and build your own PCBMotors. We can provide you with schematic for the control driver free of charge, and then you can build this on your own as well. http://pcbmotor.com/information/4a-do-it-yourself-free-layout-27/

Question: Does PCBMotor deliver the rotor?

 Answer: The rotor is part of your application and therefore not a part of our deliveries.

Question: Does the stator need to be able to vibrate freely or could the stator also be a rigid element onto which the piezos are mounted?

Answer: Yes, the stator needs to be free, and this is done by the “landing bridges” which also are routing the wires to the stator ring where the piezo’s are mounted.

Question: What about fatigue when the stator has to be "suspended freely" both for the stator itself but also for the elements connecting to the "fixed world"?

Answer: FR4 (the PCB) material is a very flexible material, and our test so far has not shown any signs of fatigue, as long as the production tolerances are kept. See also the data sheet for life time test.

Question: Does the system (motor plus driver) have to be (individually) tuned to obtain the desired specs? In other words: when manufacturing in volume and considering all tolerances of the parts (mechanical, electrical and piezos) does each assembly have to be individually calibrated?

Answer: No. By measuring the DC supply current to the motor driver, and make a frequency sweep to determine the optimal drive frequency. This can be done during manufacturing as well as every time the motor is turned on. The motor resonance frequency is mostly determined by mechanical constants of the PCB-material and it is necessary to compensate for the change in resonance frequency for the best performance over temperature. For continuous operation the new tracking feature in our Development box version 4 is an effective way of setting the optimum frequency to compensate for the self-heating in the motor. This feature is implemented in or development box, and we recommend to include this feature in your microcontroller Software making the system self calibrated. See the manual for development box for further details. Source code for the Development box is included as part of the package.

Question: What is in it for me as a customer?

Answer: You can improve your market position by offering your customers state of the art technology / application AND saving them money at the same time. Offer your customers faster, smaller and cheaper motors.

• That’s because of the innovative design of PCBMotor:

• Mounted directly on PCB - all electronics (driver) and motor are integrated into the PCB itself - uses less material and space

• Multiple motors on one card – unbelievable design flexibility

• Flat with no gears or connections – makes it more robust

• Fast start and stop – increases accuracy

• Optional position sensor

Question: What is in it for PCBMotor?

Answer: We’ve patented the technology to use a PCB as a motor. We want to spread the use of this new technology and will earn our investment by being sole supplier of piezo components for use in PCBMotors.

Question: What’s the difference between an electronic motor and a PCBMotor?

Answer: By driving the integration of the motor (including electronics) into the PCB itself we are facilitating design of smaller, cheaper and faster applications.

• PCBMotor uses less space and material.

• Electronics (driver) and motor is mounted directly on the PCB – flat and without gears and connections.

• PCB gives much more design flexibility – multiple motors can be mounted on one card.

• PCBMotor is non-magnetic.

• PCBMotor can generate more power and torque at a lower speed (with no gear) than an electric motor of comparable size.

• PCBMotor has a faster start and stop than electrical motors – giving more accuracy to the application.