5KW BLDC Motor Controller wiring

[Jusp]

I am about to test my 5kW motor with its VEC300 controller.
The wiring is quite straightforward and described in https://www.goldenmotor.com/controllers/VEC%20Controller%20Wiring%20Diagram.jpg
However, before I potentially damage anything I want to be sure I understand all the inputs and outputs. I am unable to find a user manual, hence my post.

Throttle  : seems simple, GND and 5V power the throttle, which delivers 0 to 5V back depending on the throttle setting

Brake     : GND and 5V. Is this an input to order braking, or an output actuating a (mechanical) brake? The wire labels GND/5V make me suspect it is an output.
                  What I hope it is is an input, so that connecting these two wires will start braking on the motor, regenerating kinetic energy into my batteries.
                  If this is not the case, does this controller support regeneration?
                 
High brake : 12V. What is this?

e-lock  : Seems simple. Connecting these wires will enable/unlock the system

Forward/Reverse : Seems simple. Connecting the wires will reverse the motor direction

Speed Cruise : Seems simple. Connecting the wires will start "Speed Cruising". But what is that exactly? Setting the current speed as in a cruise control?

Any explanation appreciated.

Thanks,

Juul

[Bikemad]

Hi Juul,

With the VEC-300 controller, the throttle can work in 2 ways by selecting Hyperbola or Linear in the programming software.
The linear setting is used for a conventional car or bike throttle that goes from zero when released to maximum power at full throttle.
The Hyperbola setting allows a centre biased throttle tobe used, which will increase the Forward and Reverse rpm from the centre neutral position in relation to the direction the throttle is moved, which is more suitable for boat use.
In Hyperbola mode there is not much point in wiring up a separate Reverse switch to join the two reverse wires together. 

The "High brake : 12V" is used when the vehicle already has a 12V brake light system fitted, and the 12V feed to the brake lights is used instead of having to fit a separate brake switch to join the +5V and Brake wire together.

Applying the brakes (by sending 12V to the High Brake or joining the +5V Brake and GND wires) will automatically shut off the power to the motor and simultaneously activate regen.

The Cruise function is basically used to electronically lock the controller in a predetermined throttle position. This is achieved by holding the throttle at the desired position and then momentarily pressing the cruise button to hold the throttle setting until the cruise button is pressed again or the brakes are applied.

This Cruise function would not be of much use on a boat if it is already equipped with a friction type throttle that automatically remains in the last set position when it is released. 

Alan
 

[Jusp]

Ah, that is totally clear. Thanks Alan, I will start wiring

[Jusp]

It works! Connected the controller, motor, batteries and a foot pedal (not very appropriate for a boat ), and shorted the e-lock.
After that I could let the motor spin using the foot pedal. I did not try the programming interface yet, because I am normally a Linux user, so must find a Windows laptop for running the programming app.

Two concerns:

   - I  powered on the system by attaching the last cable between the batteries (don't have a proper contactor yet). Even with the foot pedal in the off position this gave quite a spark.
     This seems to indicate that the system with motor not running still draws quite some power. The foot pedal also has a switch that shorts when one starts pressing the pedal; I did not connect that switch.
     Is this idle load expected? Or should the pedal switch connect to the brake?

  - When powering on the controller led blinked/beeped once, which according to the manual indicates "battery voltage higher than default". That seems correct, because my bank of 8 Interstate 6V golf chart batteries measures 52V when full.
    The motor seemed to work fine, and I guess I can reprogram the default voltage, but does this higher voltage hurt in the long (or short) run? And would this be the reason for the spark, the controller shorting some for getting the voltage down?

Juul

[Bikemad]

Hi Juul,

The spark you experienced is caused by the sudden inrush current that is charging the capacitors in the controller up to full battery voltage. This current quickly drops away as the capacitors are instantly charged up.
I have not seen a figure for the residual current draw of the VEC-300 controller but I would expect it to be less than 50mA (0.05A).

A pre-charge resistor can be used to limit the current for a second or two before connecting the controller directly to the battery (i.e PreCharge the controller through the resistor using a momentary push switch before energising the contactor).

A momentary push switch and a 30 Ohm resistor can be used to pre-charge the capacitors in the controller before operating the contactor to eliminate the arcing at the contactor contacts and reduce the stress on the capacitors:



Check out this post for more details on the precharge resistor.

There should be very little current draw on the battery once the capacitors are charged and the throttle is not being operated.

A single blink from the LED is normal (power on self test of the LED) when first powering up the controller, however, a regular series of single blinks would indicate "battery voltage higher than default".

52V is perfectly fine, a 16S LiFePO4 battery pack is 58.4V fully charged.

I don't know whether the GM USB cable and programming software will work with a Windows emulator installed on a Linux laptop, but it might be worth trying it. 

Alan
 
EDIT: Additional information added.

[Tommycat]

A pre-charge resistor can be used to limit the current for a second or two before connecting the controller directly to the battery (i.e PreCharge the controller through the resistor using a momentary push switch before energising the contactor).

Alan

A product such as XT90S connector might be something you would want to concider at your battery voltage. As it contains a pre charge resistor circuit that you only have to plug it in slowly to work... as opposed to extra components and wiring. 


See an example here...

https://lunacycle.com/batteries/connectors/black-xt90-spark-resistant-connector-male-female-set/

[Bikemad]

A 90 Amp connector might struggle to cope with the high current load from the 5kW motor running at full power, which, according to the dynamometer data, can be in excess of 175 Amps! 

Alan
 

[Tommycat]

Yikes... yes I was just looking at the 52 voltage of the batteries, not the amperage. Good catch Alan!   

[Jusp]

Thanks for all the info. This really gets me up to speed.

On the pre charging circuit, this should be a low amp circuit in parallel to the contactor. A sufficiently high resistor will guarantee that.

 I already planned to power my contactor from the 12V house battery. It should not be too hard to get some electronics that first switches on the precharger, and then the contactor with a delay of a few secs. A $1 microprocessor with two relays may do the job. This is a boat, so a startup time of up to half a minute should not hurt. But I do like something automatic that people cannot forget or ignore.
Do you have any idea on the capacity of the controller capacitors?

[Jusp]

Checked digikey.com, a relay rated 10 amps at 250V max, at 12V coil voltage costs $1.30.
At Alan's suggested 30 Ohms the precharge current is about 1.5 amps, which the relay should be able to easily handle. Charging a 1F capacitor (probably somewhat larger than the one in the controller, but hey, I saw a fair spark) should take some 30 secs.

[Tommycat]

Keep in mind that the resistor has to be able to handle the wattage produced. I notice that Kelly controllers recommend a 1K/10watt pre-charge resistor for their controllers up to 72 volts.


As at 52 volts and 1.5 amps = 78 watts.   

But with a 1K resistor at 52 volts = .052 amps = 2.7 watts.

Granted it's only for a short duration...  But even with this seemingly large increase in resistance, I would think charging would take place in a matter of a few seconds.

[Jusp]

Correct, and thanks for reminding. I was just ordering some 100Watts resistors. These are not typically available in micro electronics stores
I am still not sure what the capacity is that I need to charge, and wanted to stay on the safe side, so am ordering a few, 30, 50 and 100 ohms. I prefer a bit higher because that gives a gentler current, but also want to keep the charging time down. As soon as I have the resistors I will put a voltage meter on it during charging to see what I am dealing with.

[Jusp]

Ah, 1k. I was still working from Alan's suggestion of 30 Ohms. 
1k gives a way more common wattage that I can buy around the corner.
Let me try that first. I can at least determine the capacitance with them.

[Jusp]

Just to conclude this thread, here is what I will end up doing.

First, an 1kOhm shunt resistor does not work:  this indeed starts charging the capacitors, initially increasing the voltage to the controller, but the controller starts booting around 27V, drawing too much current at that stage for the voltage to increase any further towards the full 54V.

However, a 100 Ohm resistor is able to bring it up to about 49V. The remaining 5V can then be safely bridged by closing the contactor, after which the motor controller is in business. I am using 10 resistors of 1K each in parallel. Each of them is rated 1watt, which is a little bit low, but this appears to give no problem in practice because the current through them tapers off quite quickly.

Attached is a sketch of a simple microcontroller circuit using two relays, that first connects the battery to the motor controller via a 100 Ohm shunt resistor for a few seconds via Relay1, then activates the contactor via Relay2 (and releases the shunt) for bringing the motor controller in full contact with the battery. Note that this circuit is powered by my 12V house battery. The microcontroller requires 5V, which is provided by a 7805 voltage regulator. The total component cost is lower than $20, available at any microelectronics store or web site. I am using Digikey.com (relay part no Z2352-ND ). Note that I have not mentioned here anything about the (simple) program that runs on the microcontroller. Anyone interested in that shoot me a message.

Of course, having a microcontroller available now opens up other possibilities. For example, I can place it between the throttle and the motor controller to gradually increase or decrease the motor RPM towards the throttle setting in order to prevent the motor from jerking the propeller shaft. But that is another post

Thanks again Alan and Tommycat, for getting me going on this

Juul

[Jusp]

Ai, too hasty with this diagram: the contactor coil should still be in the 12V circuit.
Here is the update. One relay only, plus the ZJ400D