In a fuel cell vehicle, it is desirable to control distribution of electric power generated from a fuel cell to various components of the vehicle. When controlling the power distribution of the fuel cell vehicle, it is extremely important to estimate power of auxiliary systems such as an air compressor for supplying air to a cathode of the fuel cell by operating a motor, a pump for circulating cooling water cooling the fuel cell stack, a radiator fan, an air conditioner, etc. However, power of the fuel cell stack and of a high voltage battery may be precisely estimated by using current sensors provided at respective output ends. A motor of a driving system connected to driving wheels of a vehicle may estimate power consumption on the basis of a prediction value of torque. In contrast, other auxiliary systems for a vehicle are not provided with respective individual sensors, and thus it is impossible to precisely estimate power consumption.
Particularly, an air compressor including a motor to supply air to the fuel cell consumes approximately 10% of the total power of the fuel cell stack, and thus it is important to precisely estimate power consumption of the motor of the air compressor in order to enhance precision in power distribution control. However, it is difficult to precisely estimate power consumption. Particularly, the air compressor supplies air required for reaction with the fuel, to the fuel cell stack, and thus speed variation of the motor of the air compressor is wide depending on variation of the power of the fuel cell. Due to this, power of the motor of the air compressor varies depending on driving speed, and power consumption is different depending on acceleration, deceleration, and constant speed states at the same speed. Thus, it is extremely difficult to estimate power consumption of the motor of the air compressor.
In the fuel cell vehicle, it is desirable to precisely estimate power consumption of the above-described air compressor for tactical control of the power of the fuel cell stack and charging-discharging amount of the battery. For example, when a driver attempts to achieve wide open throttle (WOT) acceleration and the estimation in power consumption of the air compressor is incorrect, the motor consumes as much or as little energy of the fuel cell or the high voltage battery as the estimation error of the power consumption of the air compressor. When the air compressor consumes the energy more, the fuel cell or the battery consumes the energy beyond an acceptable maximum output. Thus, the fuel cell and the battery may be damaged. When the air compressor consumes the energy less, air supply to the fuel cell is insufficient. Thus, it is difficult to provide power performance required from the vehicle.
Conventionally, a map mapping power consumption onto flow rate of an air compressor or rotational speed of a motor through a test is used to estimate power consumption of the air compressor. However, in this way, as described above, power consumption of the motor of the air compressor is different depending on driving states such as acceleration, deceleration, and constant speed, and levels of acceleration and deceleration at the same rotational speed (or flow rate of air being supplied by an air compressor) condition. Thus, it is difficult to precisely estimate power consumption.
As described above, the fuel cell vehicle requires technology for accurately estimating power consumption of an air compressor supplying air to a fuel cell, more precisely, power consumption of a motor in the air compressor.
The foregoing is intended merely to aid in the understanding of the background of the present disclosure, and is not intended to mean that the present disclosure falls within the purview of the related art that is already known to those skilled in the art.
USPTO Backgrounds
USPTO Backgrounds