OK, I did an inspection tear down of the RESUN 15000 Wavemaker OEM controller.
My findings:
The external power pack is nothing but a transformer: 220-240 VAC 50/60 Hz 1500 mA; No taps; With a 120 V cord.
Major internals of the OEM controller are:
(D11) KBU 808 Bridge rectifier 8 A at 800 V ; Yea 800 V, a little ridiculous, someone had to have had a sale.
(IC5) LM2576T-ADJ (Adustible switching regulator, 3A step down (7-40 V input) Datasheet:
https://www.electro-tech-online.com/custompdfs/2012/06/lm2576-1.pdf
Fuse - Yeah
(IC1) 7805 - 5V regulator
NE555 - 555 timer, probably because the timing is out of the range of the 4528 (SMALL)
HEF4528 (MIDDLE)
HEF4528 (BIG)
Small, middle and big are labels for the potentiometers on the controller case.
The coaxial output connector is labeled (DC-OUT)
Off the bat, I see three things that should be changed.
* 2 diodes need to be added to protect the regulator from Back EMF of the motor.
* The capacitor on the switching regulator filter is an SHK 100uf @ 25 VDC. It's a 105 C rated cap, but I have my doubts that it;s high ripple rated and it needs to be. A 25 VDC rating is too small.
So with a 24 VAC input, the DC would be about 33.6 VDC which is too close to the 40 Volt limit. This means that there is no transient protection so either a MOV is needed and/or use a LM2576HV
This basically means the controller would have a habit of blowing up. Precisely the LM2576 will fail and that's what has been reported. It's nicely layed out and put together.
I doubt there is any PWMMing going on in the controller. No electrical measurements yet. Joe forgot to enclose the instructions. It could be powered up using DC.
I do think the motor has more issues than the controller. The OEM controller can easily be upgraded to be more reliable, but so what.
PWMing the OEM motor is probably more detrimental than operating it at constant voltages.
The Zetex ZXBM series of parts is not a bad controller chip. For a motor with PWM input, a Locked rotor output and a 24 VDC supply, there are a lot of parts.
Unfortunately having a Locked rotor flag seems to be important for a reef tank.
In any event, I'm convinced that:
1) The OEM controller is unreliable. The Switching regulator is prone to failures
2) The motor is unreliable because NONE of the practices suggested by FAN/motor controllers are being followed.
3) The 3 AMP current limiting of the OEM controller is beneficial.
4) No current limiting may be the biggest reason for the premature failure of the built controller.
5) Voltage Spikes are probably the biggest killer of the motor.
6) The motor windings are not likely to fail. Large conductors and plenty of cooling.
7) I don't like the choice of the coaxial power connectors. A 5 Amp locking coaxial connector would be better in my opinion.
This isn't very promising for a REEF tank that needs to operate 24/7/365
Joe didn't provide instructions or the other pieces of the puzzle such as the motor armature etc. so I can't make any comments about those parts.
What can be tried for the built controller assuming no motor changes possible:
1) Reversed biased Diode across 8A supply
2) Reversed biased Diode across the wires heading toward the motor.
3) MOV across wires leading to motor.
4) Slow start - that was a good thing
5) Some sort of an alarm (Motor currents out of range)
6) Find a better power connector (5 A locking coaxial minimum) Check temperature at connector wires.
7) Use a fully protected low side or high side driver
8) Current limiting for each motor is probably more effective than a fuse
9) Don't try to PWM the OEM motor.
Most reliable long term, possibly impossible, solution:
1) Redesign the internal motor controller
............Two basic designs possible
.............. a) Use a simple chip, reduced parts count, no error flag, change voltage to motor to
...................change speed.
................b) Use a more complex part (ZXBM series)
......................1) Use a PWM signal (not power) to change speed (suggested)
......................2) Use a control voltage to change speed (possible, but not both)
......................3) Higher parts count, not enough real estate
......................4) Bring out a locked rotor signal (alarm)
......................5) Bring out the FG (Frequency Generator) signal (future)
..............................a) it allows a way to access the health of the motor.
......................6) Stator Temperature monitoring
..............................b) Benefits questionable
Providing one could get a pump motor apart without damaging it or buy one unassembled. Both may be impossible. Putting together a simple better controller seems easily doable.
It might be too hard to use the ZXBM parts because of not enough real estate.
Enough for today.