CHP and Engine Instrumentation and Control . October 2007.
October 1st. 2007 Update.
It has become clear that some form of instrumentation and controls are needed to monitor the output
and performance of the CHP system and to provide some degree of automatic control.
Whilst it might not be desirable to have the engine self-start under automatic control because of the
safety implications, it would be of great benefit if the engine can be started on a keyswitch or by remote
signal.
Some of the automatic functions of the original "Startomatic" are desirable, and with improved
performance measurements made possible with modern microcontroller based circuitry and
appropriate sensors.
Battery monitoring is also desirable, to avoid any unsuspected shut downs of the inverter caused by
batteries reaching the low voltage point. A simple remote display of battery voltage, placed visible in
the office would be a good starting point.
Temperature sensors, flow meters and level sensors will be needed as well as engine rpm, battery volts,
battery current and inverter current monitoring.
The new electricity meter on the inverter has a convenient volts-free pulse output which can be used to
track the Wh consumed by loads connected to the inverter and also provide some degree of automatic
load monitoring.
Automatic engine stop/ start and emergency shutdown would also be desirable.
Temperature sensors can be simple thermistor types. Up to 8 or 16 analogue channels could be
multiplexed into an ADC channel using 8 to 1 analogue multiplexers.
1. Ambient temperature
2. DC generator temperature
3. Return water temperature
4. Heat exchanger outlet temperature
5. Thermal store temperature
6. Flow temperature
7. Coolant outlet temperature
8. Oil temperature
9. Fuel/injector temperature.
Then we have the parameters associated with the battery and inverter
10. Battery voltage
11. Battery charge current
12. Battery discharge current (inverter current).
13. Watt hour pulse
14. Engine rpm
15. ST alternator field current
Up to 8 relay or contactor drive signals will be needed and a couple of PWM or DAC voltage output
channels for speed control
1. Main generator contactor
2. Battery isolator
3. Inverter enable
4. engine fuel rack/shutdown
5. Engine decompress
6. ST/Inverter change over contactor
7. ST field drive
8. Glowplug preheater drive.
9. Fuel preheater drive
It has become clear that some form of instrumentation and controls are needed to monitor the output
and performance of the CHP system and to provide some degree of automatic control.
Whilst it might not be desirable to have the engine self-start under automatic control because of the
safety implications, it would be of great benefit if the engine can be started on a keyswitch or by remote
signal.
Some of the automatic functions of the original "Startomatic" are desirable, and with improved
performance measurements made possible with modern microcontroller based circuitry and
appropriate sensors.
Battery monitoring is also desirable, to avoid any unsuspected shut downs of the inverter caused by
batteries reaching the low voltage point. A simple remote display of battery voltage, placed visible in
the office would be a good starting point.
Temperature sensors, flow meters and level sensors will be needed as well as engine rpm, battery volts,
battery current and inverter current monitoring.
The new electricity meter on the inverter has a convenient volts-free pulse output which can be used to
track the Wh consumed by loads connected to the inverter and also provide some degree of automatic
load monitoring.
Automatic engine stop/ start and emergency shutdown would also be desirable.
Temperature sensors can be simple thermistor types. Up to 8 or 16 analogue channels could be
multiplexed into an ADC channel using 8 to 1 analogue multiplexers.
1. Ambient temperature
2. DC generator temperature
3. Return water temperature
4. Heat exchanger outlet temperature
5. Thermal store temperature
6. Flow temperature
7. Coolant outlet temperature
8. Oil temperature
9. Fuel/injector temperature.
Then we have the parameters associated with the battery and inverter
10. Battery voltage
11. Battery charge current
12. Battery discharge current (inverter current).
13. Watt hour pulse
14. Engine rpm
15. ST alternator field current
Up to 8 relay or contactor drive signals will be needed and a couple of PWM or DAC voltage output
channels for speed control
1. Main generator contactor
2. Battery isolator
3. Inverter enable
4. engine fuel rack/shutdown
5. Engine decompress
6. ST/Inverter change over contactor
7. ST field drive
8. Glowplug preheater drive.
9. Fuel preheater drive
The controller board was one I developed for an earlier project. It can accept either PIC16F877A or
PIC18F452.
It has 8 relay drive outputs, 8 digital inputs and 8 analogue inputs. Adding an analogue multiplexer to
this unit would allow a greater number of temperature monitoring channels.
The unit has isolated RS232 and the means to fit on-board RF transceiver modules - such as the LPRS
Easy Radio type.
The unit is powered from a dc supply, such as a small 6V or 12V gel battery.
The unit would monitor the main system parameters and forward them either by a wired RS232
connection or wireless link to a PC datalogger or display panel.
PIC18F452.
It has 8 relay drive outputs, 8 digital inputs and 8 analogue inputs. Adding an analogue multiplexer to
this unit would allow a greater number of temperature monitoring channels.
The unit has isolated RS232 and the means to fit on-board RF transceiver modules - such as the LPRS
Easy Radio type.
The unit is powered from a dc supply, such as a small 6V or 12V gel battery.
The unit would monitor the main system parameters and forward them either by a wired RS232
connection or wireless link to a PC datalogger or display panel.
Notes on Automatic operation
The Lister can be automatically started using the dc starter generator. Currently the semi-manual
approach is taken
0. Ensure that circulation pump is running!
1. Check fuel rack is open
2. Decompress engine
3. Energise the motor from the battery "taps" starting at 12V and working up to 108V. Keep the
starter connected to each tap for 5 seconds to allow momentum to build up.
4. Re-compress the engine.
5. Allow 5 minute warm up period then switch to low compression setting.
A low-side mosfet controller of about 100A motor current could be used to start the dc motor, and bring
the engine up to speed. Solenoids could be used for the fuel rack and decompressor functions.
Monitoring the motor rpm and the current magintude and direction from the starter/generator will
indicate at what point the engine starts.
For cold weather starting a glow-plug pre-heat period will probably be needed.
The Lister can be automatically started using the dc starter generator. Currently the semi-manual
approach is taken
0. Ensure that circulation pump is running!
1. Check fuel rack is open
2. Decompress engine
3. Energise the motor from the battery "taps" starting at 12V and working up to 108V. Keep the
starter connected to each tap for 5 seconds to allow momentum to build up.
4. Re-compress the engine.
5. Allow 5 minute warm up period then switch to low compression setting.
A low-side mosfet controller of about 100A motor current could be used to start the dc motor, and bring
the engine up to speed. Solenoids could be used for the fuel rack and decompressor functions.
Monitoring the motor rpm and the current magintude and direction from the starter/generator will
indicate at what point the engine starts.
For cold weather starting a glow-plug pre-heat period will probably be needed.
White Knight
White Knight is not right,
He don't look so bright,
His drum's quite tight.
Maybe I'll find when I plug in the line
That it's free, free to spin free.
White Knight is a long way from home.
I don't need a damp Tee,
I don't want wet jeans,
He can't dry, I can see.
Maybe I'll hang all my stuff on the line
When I'm free, to do laundry.
White Knight is a long way from home.
Massive apologies to Deep Purple.
White Knight is not right,
He don't look so bright,
His drum's quite tight.
Maybe I'll find when I plug in the line
That it's free, free to spin free.
White Knight is a long way from home.
I don't need a damp Tee,
I don't want wet jeans,
He can't dry, I can see.
Maybe I'll hang all my stuff on the line
When I'm free, to do laundry.
White Knight is a long way from home.
Massive apologies to Deep Purple.
