dan-graham
New Member
Hello all, my first post. I am looking for help with my project, building a CHP generator. Most of the mechanics are finished and I am now starting on wiring etc.
Background info, I have a single cylinder diesel engine, connected to a 5KW AC alternator. There is also an 180V PM motor via belt to flywheel of engine, used to start engine and provide 180VDC when engine is running. There are also 2x 3KVA inverters (UPS's APC type 48V) I also have 16x 100AH VRLA batteries. I also have smaller SLA 12V 7AH type etc etc...
What I want to achieve? Well my plan is to use 8x 12V 7AH batteries in series to crank the engine via the PM motor, (I need to build a soft start system to do this). I have tested the motor and around 80V is enough to start the engine a small 96V bank will be more than enough to crank it. When testing the motor with a relay we were seeing around 18A @ 80V so soft start would be good.
Once the engine is running and warmed up (AC @ 50HZ) the PM motor puts out 173V, as the AC is loaded and unloaded this will fluctuate max 190V. I need to step this down to 48V to feed my battery bank. Multiple outputs would be good if I could have 14.5V & 5V for other applications.
The idea is to use 1 inverter overnight, direct from battery with engine off (control required) then in the morning the engine will start up and charge the battery bank for inverter 1, while inverter 2 will provide mains from alternator and fall over to battery if there is a problem. Inverter 2 will charge its bank from the AC inverter 1 will operate in the cold start mode i.e. no AC supply. I will also pull AC direct from alternator in workshop for welder, plasma etc.
The engine is controlled by a 1940 design governor and diesel pump. I would like to remove this and attach a servo to the diesel pump control and control the engine based on the AC HZ from synchronous alternator. The old governor is not very good. At present if I connect a 3KW load to the AC it dips to 46HZ and is slow to recover, once 3KW load is removed it then over revs to 55HZ and again is slow to recover. Servo with control from AC feedback should be much more stable.
I am looking at developing a microcontroller to run the whole system and safety features. Not sure what controller offers the best features etc. I am new to microcontrollers so will probably buy a kit and work from there. There is also a heat exchanger to provide hot water, this will go through some diversion valves etc and need to be controlled. I have been looking at SMPS power supply for the DC/DC converter but not sure on components that will take the power or if I can parallel certain fet’s etc????
I am sure you will all have lots of input and can help me in the right direction before I waste money on components that are not suitable.
I would like to start with an MC that will offer most of the features I need and build from that, I have been looking at the PIC32 and various AVR’s but not sure where to start because there are a lot of systems to control. I am currently working my way through some Ibrahim books but I learn by doing rather than reading!
Thanks in advance Dan.
Background info, I have a single cylinder diesel engine, connected to a 5KW AC alternator. There is also an 180V PM motor via belt to flywheel of engine, used to start engine and provide 180VDC when engine is running. There are also 2x 3KVA inverters (UPS's APC type 48V) I also have 16x 100AH VRLA batteries. I also have smaller SLA 12V 7AH type etc etc...
What I want to achieve? Well my plan is to use 8x 12V 7AH batteries in series to crank the engine via the PM motor, (I need to build a soft start system to do this). I have tested the motor and around 80V is enough to start the engine a small 96V bank will be more than enough to crank it. When testing the motor with a relay we were seeing around 18A @ 80V so soft start would be good.
Once the engine is running and warmed up (AC @ 50HZ) the PM motor puts out 173V, as the AC is loaded and unloaded this will fluctuate max 190V. I need to step this down to 48V to feed my battery bank. Multiple outputs would be good if I could have 14.5V & 5V for other applications.
The idea is to use 1 inverter overnight, direct from battery with engine off (control required) then in the morning the engine will start up and charge the battery bank for inverter 1, while inverter 2 will provide mains from alternator and fall over to battery if there is a problem. Inverter 2 will charge its bank from the AC inverter 1 will operate in the cold start mode i.e. no AC supply. I will also pull AC direct from alternator in workshop for welder, plasma etc.
The engine is controlled by a 1940 design governor and diesel pump. I would like to remove this and attach a servo to the diesel pump control and control the engine based on the AC HZ from synchronous alternator. The old governor is not very good. At present if I connect a 3KW load to the AC it dips to 46HZ and is slow to recover, once 3KW load is removed it then over revs to 55HZ and again is slow to recover. Servo with control from AC feedback should be much more stable.
I am looking at developing a microcontroller to run the whole system and safety features. Not sure what controller offers the best features etc. I am new to microcontrollers so will probably buy a kit and work from there. There is also a heat exchanger to provide hot water, this will go through some diversion valves etc and need to be controlled. I have been looking at SMPS power supply for the DC/DC converter but not sure on components that will take the power or if I can parallel certain fet’s etc????
I am sure you will all have lots of input and can help me in the right direction before I waste money on components that are not suitable.
I would like to start with an MC that will offer most of the features I need and build from that, I have been looking at the PIC32 and various AVR’s but not sure where to start because there are a lot of systems to control. I am currently working my way through some Ibrahim books but I learn by doing rather than reading!
Thanks in advance Dan.