SYSTEM FOR OPERATING AN ELECTRIC TURNING MACHINE OPERATIVELY CONNECTED TO AN INTERNAL COMBUSTION ENGINE
A system for operating an electric turning machine (ETM) operatively connected to an internal combustion engine (ICE) are disclosed. An engine control unit (ECU) controls the ETM to operate as a motor with a first control strategy and as a generator with a second control strategy. The second control strategy is distinct from the first control strategy. The ECU controls switching the operation of the ETM from the first control strategy to the second control strategy when a sensor senses that a rotational speed of the ICE is equal to or above a minimum revolution threshold.
1 . A system for operating an electric turning machine (ETM) operatively connected to an internal combustion engine, the system comprising:
a sensor of a rotational speed of the internal combustion engine; and
an engine control unit operatively connected to the sensor of the rotational speed of the internal combustion engine, the engine control unit being adapted for:
controlling an operation of the ETM as a motor with a first control strategy;
controlling an operation of the ETM as a generator with a second control strategy, the second control strategy being distinct from the first control strategy; and
switching from the first control strategy to the second control strategy when the rotational speed of the internal combustion engine is equal to or above a minimum revolution threshold.
2 . The system of claim 1 , further comprising:
a sensor of a voltage of the ETM, the sensor of the voltage being operatively connected to the engine control unit;
wherein the engine control unit is adapted for switching from the first control strategy to the second control strategy when a voltage of the ETM is equal to or above a voltage generation threshold.
3 . The system of claim 1 , further comprising:
a timer operatively connected to the engine control unit;
wherein the engine control unit is adapted for using timing information from the timer to switch from the first control strategy to the second control strategy when the ETM has been operating with the first control strategy for at least a minimum time duration.
4 . The system of claim 1 , wherein the engine control unit is adapted for operating the ETM as a generator in the first control strategy before switching from the first control strategy to the second control strategy.
5 . The system of claim 1 , wherein the ETM operates as a starter for the internal combustion engine while controlling the ETM with the first control strategy.
6 . The system of claim 1 , further comprising:
a power source; and
an electrical converter electrically connected to the ETM and to the power source;
wherein the engine control unit is adapted for using pulse-width modulation (PWM) to control the electrical converter, the first control strategy including first calculations to determine first widths and first timings of pulses delivered to the electrical converter, the second control strategy including second calculations different from the first calculations to determine second widths and second timings of pulses delivered to the electrical converter.
7 . The system of claim 1 , wherein the first control strategy comprises a vector control, the vector control comprising:
a control by the engine control unit of a delivery of electric power from a power source to the ETM based on a pre-determined torque request sufficient to cause rotation of the internal combustion engine.
8 . The system of claim 1 , wherein the first control strategy comprises a vector control, the vector control comprising:
a determination by the engine control unit of a speed request sufficient to start the internal combustion engine; and
a control by the engine control unit of a delivery of electric power from a power source to the ETM based on the determined speed request.
9 . The system of claim 1 , further comprising:
an electrical converter electrically connected to an output of the ETM; and
a sensor of a voltage at the output of the ETM, the sensor of the voltage being operatively connected to the engine control unit;
wherein the engine control unit is adapted for causing the electrical converter to shunt the output of the ETM when the ETM is operating as a generator if the ETM generates a voltage that exceeds a maximum voltage threshold.
10 . The system of claim 9 , further comprising:
a crankshaft position sensor operatively connected to the engine control unit and adapted for detecting a mechanical position of a crankshaft of the internal combustion engine;
wherein the engine control unit is adapted for:
calculating an equivalent electrical angle of the motor-generator based on the mechanical position of the crankshaft and on a number of pole pairs of the motor-generator;
initiating shunting the output of the ETM in synchrony with a voltage rise of the motor-generator.
11 . The system of claim 1 , further comprising an accessory and a power source electrically connected to the ETM, wherein:
while operating with the first control strategy, the engine control unit causes delivering electric power from the power source to the ETM; and
while operating with the second control strategy, the engine control unit causes delivering electric power from the ETM to the accessory.
12 . The system of claim 11 , wherein the ETM is adapted for delivering electric power to the accessory at a desired voltage over a broad range of a rotational speed of the internal combustion engine when operating with the second control strategy.
13 . The system of claim 11 , wherein the power source is selected from a battery and a capacitance.
14 . The system of claim 11 , wherein the accessory is the power source, the ETM operating as a generator to charge the power source when being operating under the second control strategy.
15 . The system of claim 14 , further comprising a sensor of a start command, wherein:
the sensor of the start command is operatively connected to the engine control unit; and
the engine control unit is adapted for causing delivering electric power to the ETM using the first control strategy in response to sensing a command to start the internal combustion engine.
16 . The system of claim 15 , further comprising a sensor of a voltage of the power source, wherein:
the sensor of the voltage of the power source is operatively connected to the engine control unit; and
the engine control unit is adapted for causing electric power being delivered using the first control strategy if a voltage of the power source is equal to or above a first minimum voltage threshold.
17 . The system of claim 16 , further comprising a display, wherein:
the display is operatively connected to the engine control unit; and
the engine control unit is adapted for causing the display to provide a manual start indication if the voltage of the power source is below the first minimum voltage threshold.
18 . The system of claim 16 , wherein the engine control unit is adapted for causing terminating the delivery of electric power if the voltage of the power source falls below a second minimum voltage threshold lower than the first minimum voltage threshold.
19 . The system of claim 18 , further comprising a display, wherein:
the display is operatively connected to the engine control unit; and
the engine control unit is adapted for causing the display to provide a manual start indication when terminating the delivery of electric power.
20 . The system of claim 1 , wherein:
the ETM is a multi-phase motor-generator, operating as a starter and as a generator.
21 . The system of claim 20 , further comprising:
an inverter electrically connected to a multi-phase output of the multi-phase motor-generator; and
a sensor of a voltage at the multi-phase output of the multi-phase motor-generator, the sensor of the voltage being operatively connected to the engine control unit;
wherein the engine control unit is adapted for causing the inverter to shunt one or more phases of the multi-phase motor-generator when operating as a generator if the multi-phase motor-generator generates a voltage that exceeds a maximum voltage threshold.
22 . The system of claim 21 , wherein the inverter is adapted for regulating the voltage generated by the multi-phase motor-generator in dissipative mode.
23 . The system of claim 21 , wherein the inverter is adapted for regulating the voltage generated by the multi-phase motor-generator in series mode.
24 . The system of claim 1 , wherein the internal combustion engine comprises:
a cylinder;
a cylinder head connected to the cylinder;
a piston disposed in the cylinder, the cylinder, the cylinder head and the piston defining a variable volume combustion chamber therebetween; and
a crankshaft operatively connected to the piston;
wherein the ETM is operatively connected to the crankshaft.
25 . The system of claim 24 , further comprising:
a fuel delivery system operatively connected to the engine control unit; and
an ignition system operatively connected to the engine control unit;
wherein the engine control unit is adapted for causing the fuel delivery system to deliver fuel in the combustion chamber as the piston moves toward its top dead center (TDC) position and to cause the ignition system to ignite the fuel in the combustion chamber as the piston moves beyond from its TDC position.
26 . The system of claim 25 , wherein fuel delivery system further comprises a fuel injector adapted for injecting fuel in the combustion chamber.
27 . The system of claim 26 , further comprising an absolute position sensor operatively connected to the engine control unit and adapted for detecting a mechanical position of the crankshaft, wherein the engine control unit is adapted for causing the fuel delivery system and the ignition system to respectively inject and ignite fuel in the combustion chamber according to the mechanical position of the crankshaft.