Choice off controller

In order to control the electric motor we need a controller. In its most basic form it interprets actions taken by the driver and adjusts the voltage and current to the motor accordingly. There are as many flavors of controllers as there are types of motors. A good source for finding motors and controllers that work together is www.evalbum.com.

When choosing controller you should, at least, consider the following.

·        Make sure the controller matches your type of motor, DC, AC, series and so on.

·        Make sure the controller can provide the amount of power you need for your application

·        Make sure that the controller is easy to program and that there is some kind of support mechanism that can help you if you get stuck.

I've used the Controllers from Sevcon and Kelly and its two different worlds. First of all the Sevcon Gen4 controller is AC and the Kelly is DC.

Sevcon Gen4 G4845

. Apart from that the Sevcon controller is a state of art controller with more settings than you can ever imagine. On the down side the complexity makes is very hard to program and even if you are a dealer it can be hard to get support from Sevcon. On top of that the programming interface for the Sevcon Gen4 controller costs about $900!!!

The IXXAT 1.01.0087.10200 used for programming the gen4.

Kelly on the other hand uses a USB-to-rs232 cable that you can find in any computer store to program their equipment. Kelly's downside is, if you should believe the word on the internet, their quality. I've never heard so many bad words being said about any controller/manufacturer. I didn’t really choose Kelly, it came with the motor. But I will give them an honest try. I've already started by contacting support and they answer back in a day or two.

The problem I'm facing is that the red led on the controller is on all the time. According to the manual this means that is broken but it seems to be working quite ok. I've put together a document with pictures of the controller and schematics showing how it is connected. It has all been sent to Kelly for review. Programming of the controller is done via a GUI that runs on Windows. In order to communicate with the you need the USB-to-rs232 interface. According to Kelly all external devices, such as motor, throttle should be disconnected during programming of the controller. You don’t actually need the batteries connected as you can supply the controller with a minimum of 18 volts via J1. J1 is one of the two round connectors on the front of the controller. I hooked up a PC-supply to pin 1 (+) and pin 13 (-).

Apply power and connect the db9 connector to the controller. Make sure that you have already installed drivers for the USB-to-rs232 in windows.

The controller should, when booting up, turn on the green and the red led, after a few seconds the red one should turn off.

Start the programming software, you can get it from http://kellycontroller.com/support.php make sure you pick the right software for your controller.

I should mention that this is work-in-progress and all of the settings described here might not be 100% accurate. In other words, don’t blame me if something goes wrong. ALWAYS keep your car jacked up during testing.

This is the first window that pops up after starting the application. I'm going for a basic configuration using a 0-5v throttle as the only external device. The throttle gets 5v from the controller and by moving the lever it returns 0.9-4.10 volts to the controller. The controller also includes a micro switch but we will get to that later.

First of all I specified the throttle effective starting position to 1.2 volts. This means that that the controller won't send anything to the motor if the value from the throttle is under 1.2volts. I l left the throttle effective area end position at 4 volts.

Maximum motor current specifies the maximum current that will be sent to the motor. The value is a precentage of the total current handled by the controller. The 72601 can handle 600 Amps and the Agni has a maximum apm of 300, hence the 50% setting.

! Make sure your battery pack can supply the current specified !

On the second page we will set over and under voltage. These setting are important and will protect your battery pack. These values vary depending on the battery technology used. Get the right setting from your battery supplier.

Another setting on page two is control mode this is how your controller should behave during acceleration. I've always been told to use torque and not speed. Kelly introduces  balanced and I'm guessing I will play around with these values later.

Throttle up/down rate determines how fast the controller should respond to the throttle signal

This is cool stuff, regen, regeneration of energy. Imagine that you are out driving and you run up on a red light. In order to stop you depress the brake pedal. A "normal" car does not have any means of recovering the energy generated during this phase. All the energy that kept the car moving before you pressed the brake is turned into heat. The good thing with an electric motor is that it can be turned into a generator and if your controller supports it the energy from the moving car can be returned to the battery pack instead of going up in smoke. At least that’s the theory of it.

Regen can be controlled in more than one way on the Kelly. I'll start with the simplest setup. When you step of the gas pedal regen will start! This might not be the best solution because it might be wiser to let the car freewheel down a slope then to try and capture the energy generated.

So I found out that if you connect the micro switch in the throttle to the controller you can actually decide if you want to start regen or if you want to freewheel. It works like this:

When you want to use regen you step of the pedal, but not all the way. The trick is to keep the micro switch connected.

If you want to freewheel down a long slope you let the pedal go to its starting position, which means the micro switch will be disconnected. This will deactivate regen.

See http://youtu.be/fEPFgumcJDM for more info.

When you are done with the configuration, click Finish and power-cycle the controller.