Thursday, February 6, 2014

More JM1 and JM1S Testing

We picked up testing the JM1 and JM1S where it was left off a year or so ago. The tests are being carried out at 50-65V up to 18 kW. The results of the tests are available on the product pages for each motor.

A few of the possible winding configurations for the JM1 and JM1S are listed on each motor's page. The JM1S spins about 1.6x faster than the JM1 for a given winding, so any winding posted on either page can be compared.

JM1 after a 10 kW run

Thursday, March 1, 2012

JM1U 3TY 6P test data

We have been testing the JM1U 3TY 6P and I am pleased with the results. We have made improvements in the thermal performance of the motors and they can now deliver more power at a lower winding temperature which reduces the copper losses. This motor can deliver more than 13kW continuously and has a specific power of more than 4.5kW/kg. A higher speed version may be able to reach a specific power of 6kW/kg stay tuned .....

We tested four props ranging from a 26/12 to a 37/12. The 34/10 test was run twice and you can see the two overlapping sets of data.

The following plot shows output power (kW) vs speed (RPM) vs efficiency (%). We measure the supply voltage and the supply current. The efficiency therefore includes the line losses, the controller losses, and the motor losses. In these you can see that the JM1 is most efficient at high speed and can deliver more power at higher speed. This motor was wound to deliver 13 kW continuous at 6500 RPM at 63V. The last points on the 26/12 and 30/10 curves are at full throttle. I am going to build a higher speed motor to test soon.

The following is a plot of efficiency (%) vs torque (Nm). You can see that the JM1 delivers approximately flat peak efficiency between 10 and 20 Nm of torque. In static testing there is not sufficient cooling to run the motor continuously over 21 or 22 Nm of torque.

Here is speed (RPM) vs Torque (Nm) vs efficiency (%). Please see the efficiency color scale in the chart above.

 Here is efficiency (%) vs speed (RPM).

Here is a gif of the data that gives you a sense of the efficiency surface.

We will be posting more testing data on the JM2S and a higher speed JM1 soon. We are also hard at work prototyping larger motors and generators. Please let us know if there is a motor or generator that we can help you with.


Wednesday, January 11, 2012

A few weeks ago we tested a JM1S-3TD with the and a JM1S-4TD on an earlier revision of the test stand. The efficiencies shown in the screenshot below include motor and controller losses. Based on the temperature of the motor and the temperature of the controller the majority of the losses are in the motor. I would estimate that 2-4% of the losses are in the controller and the remainder are in the motor. Thus in this torque and speed range the JM1S is running at an efficiency of 90-95%. JM1S-3TD at 50V 6500rpm and 8-10kW is a sweet spot. JM1S-4TD at 50V 5000rpm and 6-8kW seems like a sweet spot. 12-13 Nm is a happy spot for this motor. Notice the 4.4% drop in efficiency at 4400rpm going from the 34x10 to the 37x13 prop (8.9 to 17.7Nm). 

I decided to start recording our motor test results in a blog. We have been improving our motor test stands but they are still a work in progress. We are measuring the supply voltage, the current into the controller, the torque, the speed, the thrust, the ambient temperature, the temperature of the motor windings, and the temperature of the controller. We are calculating the input power, output power, efficiency, and the thrust efficiency.