PDC
05-02-2006, 04:57 AM
Got this answer on some questions on this topic form Frank Köhler.
As e-pilot I think this is something we should know something about.
Paul wrote:
Hi!
I Heard that the sparks produced when one connect the battery to the speed controller can be harmful to the speed controller, is that correct?
Sparks itself are not harmeful to the controller but the connector.
But if contact at the beginning is very good, the current flowing can be very high (nearly short circuit) leading in turn to overvoltage situation. This is because of the wiring inductance (battery and its wires to actronic) and the inbuild capacitor acting like a resonance circuit. In worst case voltage can reach twice the battery voltage.
- If yes, do you have a solution to avoid this spark?
Use a precharge circuit. This is an addition small connector associated with plus with plus of the battery (eg. 2mm connector) and a small resistor 22..56Ohms 1Watt.. Use male on the
actronic side and female on the battery side.
The male connector and the resitor are connected in series and then directly to plus of the actronic. Wire can be small
The goal is to precharge the inbuild capacitor with relatively low current via the resitor before connecting the power path. This avoid sparking and overvoltage.
You have to follow a defined procedure while connecting:
1. connect small onnector (precharge path)
2. connect minus
3. connect plus
When disconnecting , take precharge path first .
- Exactly what kind of damage can this spark do to the controller?
Due to overvoltage power transistors may be destroyed
- Is is correct that if you use the controller without any protection for the spark, then the controller can make radio interference after some time?
No, normally not. Because destruction takes place right after connecting you will not have the chance to get interference....
But spaking can and will damage connectors which may in turn lead to malfunction possibly causing interference.
- Is there anything on a controller there needs to be changed with fixed intervals?
When flying heavy duty the electrolyte condensator (is any) may get damaged because the electrolyte can evaporate thus loosing its function.
It is hard to tell how long an electrolyte capacitor may be able to work properly. This depends on may factors like:
- outside temperature
- cooling of capacitor
- motor current
- length of battery wireing
- ratio of max. possible motor speed to motor speed set. The higher tis figure is the better the speed can held constant at high power and the higher the stress of the capacitor
In our new actronic 45, actronic 80-32 and actronic 120 we replaced the electolyte capacitor by nearly undestructable ceramic capacitors.
Also on the older actronic 70-32 you have pay attention to the shrinking tube holding the heat sink in place on toip of the power transistors. In newly produced units, heat sink is glud using special adhesive (electrically insulating but thermally conducting). this adhesive is blue to white in contast to the yellow or pink foil, used previously.
Best regards
Paul
Best regards
Frank Köhler
Köhler Elektromotoren GbR
As e-pilot I think this is something we should know something about.
Paul wrote:
Hi!
I Heard that the sparks produced when one connect the battery to the speed controller can be harmful to the speed controller, is that correct?
Sparks itself are not harmeful to the controller but the connector.
But if contact at the beginning is very good, the current flowing can be very high (nearly short circuit) leading in turn to overvoltage situation. This is because of the wiring inductance (battery and its wires to actronic) and the inbuild capacitor acting like a resonance circuit. In worst case voltage can reach twice the battery voltage.
- If yes, do you have a solution to avoid this spark?
Use a precharge circuit. This is an addition small connector associated with plus with plus of the battery (eg. 2mm connector) and a small resistor 22..56Ohms 1Watt.. Use male on the
actronic side and female on the battery side.
The male connector and the resitor are connected in series and then directly to plus of the actronic. Wire can be small
The goal is to precharge the inbuild capacitor with relatively low current via the resitor before connecting the power path. This avoid sparking and overvoltage.
You have to follow a defined procedure while connecting:
1. connect small onnector (precharge path)
2. connect minus
3. connect plus
When disconnecting , take precharge path first .
- Exactly what kind of damage can this spark do to the controller?
Due to overvoltage power transistors may be destroyed
- Is is correct that if you use the controller without any protection for the spark, then the controller can make radio interference after some time?
No, normally not. Because destruction takes place right after connecting you will not have the chance to get interference....
But spaking can and will damage connectors which may in turn lead to malfunction possibly causing interference.
- Is there anything on a controller there needs to be changed with fixed intervals?
When flying heavy duty the electrolyte condensator (is any) may get damaged because the electrolyte can evaporate thus loosing its function.
It is hard to tell how long an electrolyte capacitor may be able to work properly. This depends on may factors like:
- outside temperature
- cooling of capacitor
- motor current
- length of battery wireing
- ratio of max. possible motor speed to motor speed set. The higher tis figure is the better the speed can held constant at high power and the higher the stress of the capacitor
In our new actronic 45, actronic 80-32 and actronic 120 we replaced the electolyte capacitor by nearly undestructable ceramic capacitors.
Also on the older actronic 70-32 you have pay attention to the shrinking tube holding the heat sink in place on toip of the power transistors. In newly produced units, heat sink is glud using special adhesive (electrically insulating but thermally conducting). this adhesive is blue to white in contast to the yellow or pink foil, used previously.
Best regards
Paul
Best regards
Frank Köhler
Köhler Elektromotoren GbR