1. A method for detecting a faulty connection of a low-voltage auxiliary battery (6) incorporated in an auxiliary network (5) of a motor vehicle supplied by said auxiliary battery and by a non-reversible current source (4), such as a DCDC voltage converter or an alternator, which is voltage controlled to supply an output voltage which is a function of the control setpoint voltages of said current source, wherein:
at least one minimum andor maximum voltage value, which cannot be reached by the voltage at the terminals of the auxiliary battery (6), is determined,
the function of setpoint value is assigned to the minimum andor maximum voltage value, and the current source (4) is controlled by sending said setpoint value to it,
the voltage is measured at the terminals of the auxiliary network (5),
and a faulty connection of the auxiliary battery (6) is deduced if there is a match between the measured voltage and the setpoint voltage.
2. The method as claimed in claim 1, for detecting a faulty connection of an auxiliary battery (6) consisting of a lead-acid battery with a nominal voltage of about 12 V, wherein a minimum setpoint voltage value at least substantially within the range from 8 V to 10.5 V is selected.
3. The method as claimed in claim 1, for detecting a faulty connection of an auxiliary battery (6) consisting of a lead-acid battery with a nominal voltage of about 12 V, wherein a maximum setpoint voltage value at least substantially within the range from 15 V to 16 V is selected.
4. The detection method as claimed in claim 1, wherein the function of setpoint value is assigned to a minimum voltage value which cannot be reached by the voltage at the terminals of the auxiliary network (5).
5. The detection method as claimed in claim 4, wherein the strength of the current delivered at the output of the current source (4) is measured, and in that a faulty connection of the auxiliary battery (6) is deduced when, a) there is a match between the measured voltage and the setpoint voltage, and b) the measured strength of the current at the output of the current source (4) has a non-zero value.
6. The detection method as claimed in claim 2, wherein the function of setpoint value is assigned to a minimum voltage value which cannot be reached by the voltage at the terminals of the auxiliary network (5).
7. The detection method as claimed in claim 3, wherein the function of setpoint value is assigned to a minimum voltage value which cannot be reached by the voltage at the terminals of the auxiliary network (5).
8. The detection method as claimed in claim 6, wherein the strength of the current delivered at the output of the current source (4) is measured, and in that a faulty connection of the auxiliary battery (6) is deduced when, a) there is a match between the measured voltage and the setpoint voltage, and b) the measured strength of the current at the output of the current source (4) has a non-zero value.
9. The detection method as claimed in claim 7, wherein the strength of the current delivered at the output of the current source (4) is measured, and in that a faulty connection of the auxiliary battery (6) is deduced when, a) there is a match between the measured voltage and the setpoint voltage, and b) the measured strength of the current at the output of the current source (4) has a non-zero value.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A fuel cell system comprising:
a fuel cell that generates an electric power and heat by a reaction of reaction gases;
a heat exchanger;
a coolant circuit for a coolant between the fuel cell and the heat exchanger;
a coolant circulating pump for circulating the coolant in the coolant circuit;
a drive motor for driving the coolant circulating pump, the coolant receiving and carrying the heat to the heat exchanger by the coolant circuit, the coolant circulating pump, and the drive motor; and
a control unit that controls a rotational speed of the drive motor and changes an upper limit of the rotational speed of the drive motor to control the rotational speed of the drive motor using the upper limit,
wherein the control unit determines the upper limit of the rotational speed of the drive motor on the basis of a cooling capacity of the heat exchanger.
2. The fuel system as claimed in claim 1, wherein the control unit determines the upper limit on the basis of a physical amount regarding the electric power.
3. The fuel system as claimed in claim 2, wherein the fuel system is mounted on a vehicle and the control unit determines the upper limit on the basis of a speed of the vehicle traveling using the electric power.
4. The fuel system as claimed in claim 1, further comprising a reaction gas supplying pump for supplying one of the reaction gases to the fuel cell, wherein the drive motor drives the reaction gas supplying pump as a driving source which is common to the coolant circulating pump, and the control unit determines the upper limit of the rotational speed of the drive motor on the basis of the upper limit of a flow rate of the reaction gas to the fuel cell.
5. The fuel system as claimed in claim 1, wherein the fuel system is mounted on a vehicle and the control unit comprises a reference rotational speed determining unit that determines a reference rotational speed of the drive motor on the basis of a target generation output of the fuel cell corresponding to a speed of the vehicle, a rotational speed increase value determining unit that determines an increase value of the rotational speed of the drive motor on the basis of a temperature of the coolant, and an upper limit rotational speed determining unit that determines the upper limit of the rotational speed of the drive motor on the basis of one of a speed of the vehicle and the electric power.
6. A method of controlling a fuel cell system including: a fuel cell that generates an electric power and heat by a reaction of reaction gases; a heat exchanger; a coolant circuit for a coolant between the fuel cell and the heat exchanger; a coolant circulating pump for circulating the coolant in the coolant circuit; and a drive motor for driving the coolant circulating pump, the coolant receiving and carrying the heat to the heat exchanger by the coolant circuit, the coolant circulating pump, and the drive motor; the method comprising the steps of:
(a) controlling a rotational speed of the drive motor;
(b) changing an upper limit of the rotational speed of the drive motor to control the rotational speed of the drive motor using the upper limit; and
(c) determining the upper limit of the rotational speed of the drive motor on the basis of a cooling capacity of the heat exchanger.
7. The method as claimed in claim 6, further comprising the step of:
determining the upper limit on the basis of a physical amount regarding the electric power.
8. The method as claimed in claim 7, wherein the fuel system is mounted on a vehicle, the method further comprising the step of:
determining the upper limit on the basis of a speed of the vehicle traveling using the electric power.
9. The method as claimed in claim 6, further comprising the steps of:
supplying one of the reaction gases to the fuel cell with a reaction gas supplying pump driven by the drive motor which is a common driving source to the coolant circulating pump; and
determining the upper limit of the rotational speed of the drive motor on the basis of the upper limit of a flow rate of the reaction gas to the fuel cell.
10. The method as claimed in claim 6, wherein the fuel system is mounted on a vehicle, the method further comprising the steps of:
determining a reference rotational speed of the drive motor on the basis of a target generation output of the fuel cell corresponding to a speed of the vehicle;
determining an increase value of the rotational speed of the drive motor on the basis of a temperature of the coolant; and
determining the upper limit of the rotational speed of the drive motor on the basis of one of a speed of the vehicle and the electric power.