US-20260124962-A1 - HYBRID POWER SUPPLY SYSTEM AND CONTROL METHOD THEREOF

US20260124962A1US 20260124962 A1US20260124962 A1US 20260124962A1US-20260124962-A1

Abstract

A hybrid power supply system and a control method thereof are provided. The hybrid power supply system includes a fuel cell configured to generate power, a plurality of batteries which are selectively connected to the fuel cell, a drive motor which is selectively connected to the plurality of batteries, and a controller configured to connect a battery to be charged among the plurality of batteries to the fuel cell to control charging of the battery to be charged and connect a battery to be discharged among the plurality of batteries to the drive motor to control discharging of the battery to be discharged.

Inventors

Yei Sik Jeon
Hee Sung Lim

Assignees

K-FUELCELL, INC.

Dates

Publication Date: 20260507
Application Date: 20251105
Priority Date: 20241107

Claims (10)

1 . A hybrid power supply system comprising: a fuel cell configured to generate power; a plurality of batteries which are selectively connected to the fuel cell; a drive motor which is selectively connected to the plurality of batteries; and a controller configured to connect a battery to be charged among the plurality of batteries to the fuel cell to control charging of the battery to be charged and connect a battery to be discharged among the plurality of batteries to the drive motor to control discharging of the battery to be discharged.
2 . The hybrid power supply system of claim 1 , further comprising a power relay assembly disposed on each of the plurality of batteries, wherein the power relay assembly comprises: a charge path configured to selectively connect the fuel cell and a corresponding battery among the plurality of batteries; and a discharge path separated from the charge path and configured to selectively connect the drive motor and the corresponding battery.
3 . The hybrid power supply system of claim 2 , wherein the discharge path comprises: a precharge relay; and a discharge relay connected in parallel to the precharge relay.
4 . The hybrid power supply system of claim 3 , wherein in the discharging of power from the battery to be discharged to the drive motor, the discharging is performed via the precharge relay and then via the discharge relay.
5 . The hybrid power supply system of claim 3 , wherein the discharge relay is converted to a path which supplies power generated by the drive motor to each of the plurality of batteries during regenerative braking.
6 . The hybrid power supply system of claim 1 , further comprising a battery management system disposed on each of the plurality of batteries, wherein the battery management system monitors battery information including a state of charge of a corresponding battery among the plurality of batteries and provides the battery information to the controller.
7 . The hybrid power supply system of claim 1 , wherein the controller determines a battery among the plurality of batteries as the battery to be charged in a case where a state of charge of the battery is equal to or lower than a charging start threshold and a battery among the plurality of batteries as the battery to be discharged in a case where the state of charge of the battery is equal to or higher than a charging complete threshold.
8 . A control method of a hybrid power supply system, the control method comprising: checking states of charge of a plurality of batteries; determining a battery to be discharged and a battery to be charged among the plurality of batteries; and supplying power to a drive motor by discharging the battery to be discharged and charging the battery to be charged through power generation of a fuel cell.
9 . The control method of claim 8 , wherein the states of charge of the plurality of batteries are monitored and checked by a battery management system disposed on each of the plurality of batteries.
10 . The control method of claim 8 , wherein each of the plurality of batteries is determined as the battery to be discharged in a case where the state of charge of the battery is equal to or higher than a charging complete threshold and as the battery to be charged in a case where the state of charge of the battery is equal to or lower than a charging start threshold.

Description

BACKGROUND 1. Field Embodiments of the disclosure relate to a hybrid power supply system and a control method thereof. 2. Description of the Related Art Fuel cells are a power generation device which converts chemical energy into electrical energy, which may be used to supply power to industrial, residential, and small electrical appliances and, recently, are most commonly used as a power source for vehicle propulsion. In a case where fuel cells are used in vehicles, using only fuel cells as the power source for a vehicle results in output characteristics of performance degradation in low-efficiency driving ranges and sharp output voltage drops in high-speed driving ranges, which require high voltages, thereby failing to supply sufficient voltages to meet the requirements of the drive motor, which is problematic. Sudden loads applied to a vehicle may cause sharp momentary drops in fuel cell output voltage, thereby making it difficult to supply sufficient power to the drive motor, and unidirectional output characteristics of fuel cells may prevent the recovery of energy which is input from the drive motor during vehicle braking. To compensate for these drawbacks, fuel cell hybrid vehicles each of which have a battery as a separate power source to supply electricity to the drive motor, in addition to a fuel cell, are being developed. However, due to the parallel connection structure of a fuel cell and a battery which supplies power directly from the fuel cell to the drive motor, conventional fuel cell hybrid vehicles had the following problems. First, it is difficult to supply power to the battery in a case where power is supplied from the fuel cell to the drive motor, and power from the fuel cell which charges the battery fluctuates depending on the load variation of the drive motor, which causes the battery to overheat. In addition, because the power which charges the battery is not constant, in a case where a sudden high load occurs on the vehicle and the state of charge of the battery is equal to or lower than the threshold, it is still difficult to supply sufficient power to the drive motor, thereby resulting in reduced output efficiency. Furthermore, the power output of not only batteries, but also fuel cells, is not constant and varies frequently, which is detrimental to system efficiency and fuel economy, in which the degradation of the catalyst in a fuel cell stack accelerated by the voltage fluctuations causes an adverse effect on durability. SUMMARY Embodiments of the disclosure are intended to solve the aforementioned problems and/or limitations, and have an objective to provide a hybrid power supply system and a control method thereof which enable a fuel cell to generate power at a constant output regardless of the load of a drive motor, thereby adjusting the charging rate of a battery to be constant. Another objective of embodiments of the disclosure is to provide a hybrid power supply system and a control method thereof which enable charging of the battery by supplying a constant amount of power, so that the heat generation problem of the battery may be minimized and, at the same time, the durability of the fuel cell and the efficiency of the system may be enhanced. Another objective of embodiments of the disclosure is to provide a hybrid power supply system and a control method thereof which enable the battery to be charged while the drive motor is running, so that the state of charge (SOC) of the battery may be maintained optimally and power may be supplied properly even under high load conditions of the drive motor. However, these objectives are merely illustrative and not intended to limit the scope of the disclosure. Embodiments of the disclosure provide a hybrid power supply system including: a fuel cell configured to generate power; a plurality of batteries which are selectively connected to the fuel cell; a drive motor which is selectively connected to the plurality of batteries; and a controller configured to connect a battery to be charged among the plurality of batteries to the fuel cell to control charging of the battery to be charged and connect a battery to be discharged among the plurality of batteries to the drive motor to control discharging of the battery to be discharged. In an embodiment of the disclosure, the hybrid power supply system may further include a plurality of power relay assemblies disposed on the plurality of batteries, respectively, wherein each of the power relay assemblies includes: a charge path configured to selectively connect the fuel cell and a corresponding battery among the plurality of batteries; and a discharge path separated from the charge path and configured to selectively connect the drive motor and the corresponding battery. In an embodiment of the disclosure, the discharge path may include: a precharge relay; and a discharge relay connected in parallel to the precharge relay. In an embodiment of the disclosure, in the discharging of power from