Here is an ESC with BEC That I came across some time ago. It was designed and developed by a gentleman in Germany by the name of Claus Poltermann. I have not used the ESC at this time for two reasons: i have not finished It yet and I have no boat In which to install it yet. This is an uncomplicated unit to build, and i have attached documentation and images for this unit with the developers permission. Included is the website link where you can obtain the microprocessor ask questions, and if you are not into fabricating pc boards, Obtain the pc board itself.
Keep in mind that Claus will not be available until September.
Speed controller with reverse
This is a guide to building an electronic cruise control with polarity reversal for ship models. Only readily available standard components are used and the complete documents for the construction and the firmware for the microcontroller are available for free download.
A speed controller is one of the standard applications in model electronics. The speed controller presented here (actually: "speed controller") for conventional brush motors is up to max. 8 A loadable. It is therefore suitable for ship models that should move at a prototypical speed and is sufficient for most function models. The controller is less suitable for racing boats.
The following requirements must be fulfilled for a successful replica:
* Possibility of etching circuit boards. The circuit board is single-layered and therefore easy to manufacture.
* Availability of a programming device for PIC microcontrollers
* some experience in soldering
This speed controller is available in the cp-electronics shop as a kit or as a ready-made module and has the following enhancements compared to the free firmware:
* PWM frequency selectable (2.5 kHz or 9 kHz)
* either linear or exponential control characteristics
All other properties are the same in both versions:
* Polarity reversal of the motor via relay
* Supply of the relay via the drive battery
* simple construction with standard components
* Operation with 6 V or 12 V driving battery
* Current carrying capacity max. approx. 8 A
* sensitive control through 250 speed levels per direction of travel
* Fail Safe: the engine is switched off in the event of reception errors
* Motor start protection when connecting the battery
* galvanic isolation of control and power section
* Setup function for learning the neutral and maximum position
The circuit board is single-layered and easy to manufacture with hobby tools. Please reinforce the conductor tracks that carry the motor current with a soldered bare copper wire. It also makes sense to use base material with a 70 µm copper layer (standard is 35 µm). If necessary, the conductor tracks can also be tinned thick with solder.
No tiny SMD components are used, so assembly is also possible without a microscope. Every experienced model maker should therefore be able to solder the controller without any problems.
The controller is very simple.
The receiver pulse switches the internal LED of the optocoupler via a transistor, the collector of the internal transistor is placed on an input of the PIC microcontroller. The receiver is thus galvanically isolated from the load circuit, interference signals from the motor cannot get into the receiver. However, the motor should not be carefully suppressed!
The controller is supplied with a stabilized operating voltage of 5 V from the drive battery via a voltage regulator 7805. If a 6 V battery is used, a low-drop voltage regulator should be used (see parts list).
An output of the PIC switches the polarity reversal relay via a driver transistor. The relay is powered by the drive battery, so the coil voltage must be adjusted to the voltage of the drive battery. There are suitable relays in both a 6 V and a 12 V version.
Another output controls the two MOSFETs with a PWM signal, which is generated by the microcontroller depending on the stick position on the transmitter, via a series resistor directly and without an additional driver circuit. The Schottky diode MBR 1645 feeds the current induced in the motor back into the motor during the switch-off phases of the MOSFETs. There are also two LEDs for signaling the setup and for displaying errors.
The setup of the neutral and maximum position values can be adapted to your own remote control system. For this, the jumper "SET" is inserted and the supply voltage (first receiver, then driving battery) is switched on.
After switching on, the red LED flashes for approx. 5 s, during this time the control stick and the trim must be brought into the neutral position or held there. If the LED goes out, the corresponding value has been permanently saved in the PIC's EEPROM. The green LED then flashes, the joystick must be brought to the maximum position and held there during this time.
After successful setup, the green LED lights up continuously.
If, on the other hand, the red LED lights up permanently, there is an error. Possible causes are:
* no difference between neutral and maximum position. Check whether the speed controller has been connected to the correct receiver channel.
* the measured pulse length for the neutral position is greater than the length for the maximum position. Then you have to change the transmitter or activate a servo reverse for this channel.
In the event of an error, the cause must be eliminated and the setup carried out again.
If the red LED lights up permanently after it has flashed, ie the green LED does not flash during setup, no valid receiver pulses are measured. In this case, check the connection cable and the printed circuit board for errors.
After completing the setup, the speed controller must be disconnected from the supply voltage for approx. 30 s (the capacitors must be completely discharged). The jumper is now removed and the supply voltage is switched on again. The green LED lights up for approx. 2 s, during this time the stick must not be brought out of the neutral position (tarnish protection). If the green LED goes out, the motor output is activated and the controller is ready for operation.
The setup can be carried out again if necessary.
If the red LED lights up in operating mode (SET jumper removed), this indicates faulty receiver pulses and indicates reception interference or a transmitter that is switched off.
The firmware of the microcontroller does the evaluation of the pulse length, the switching of the relay and the generation of the PWM signal for the power transistors.
In order to prevent the motor from starting when it is switched on, the stick must be held in the neutral position for approx. 2 s when the power supply is switched on, only then will the motor output become active. The same applies after the engine has stopped due to invalid receiver pulses.