US-12617315-B2 - Hydrogen fuel cell electric vehicle energy management

US12617315B2US 12617315 B2US12617315 B2US 12617315B2US-12617315-B2

Abstract

A fuel cell electric vehicle (FCEV) includes an electric traction motor configured to drive the FCEV and generate power through regenerative braking, a high voltage (HV) battery system including a HV bus and a HV battery configured to power the electric traction motor, and a fuel cell stack (FCS) configured to generate electricity to recharge the HV battery and/or power the electric traction motor. A powertrain control system for preventing over-voltage of the HV bus and HV battery includes a controller having one or more processors configured to control (i) a fuel cell power limit of the FCS, and (ii) a regenerative braking power limit of the electric traction motor. The controller is programmed to measure a voltage of the HV battery system, and selectively limit the fuel cell power limit and/or the regenerative braking power limit when the measure voltage exceeds a predetermined threshold.

Inventors

Zhentao XIE
Rudolf Kharpuri

Assignees

FCA US LLC

Dates

Publication Date: 20260505
Application Date: 20240216

Claims (13)

1 . A fuel cell electric vehicle (FCEV), comprising: an electric traction motor configured to drive the FCEV and generate power through regenerative braking; a high voltage (HV) battery system including a HV bus and a HV battery configured to power the electric traction motor; a fuel cell stack (FCS) configured to generate electricity to recharge the HV battery and/or power the electric traction motor; and a powertrain control system for preventing over-voltage of the HV bus and HV battery, including a controller having one or more processors configured to control (i) a fuel cell power limit of the FCS, and (ii) a regenerative braking power limit of the electric traction motor, wherein the controller is programmed to: measure (i) a voltage of individual battery cells of the HV battery and (ii) a voltage of the HV bus; determine an arbitrated measured voltage, which is a maximum of the measured voltage of the individual battery cells and the measured voltage of the HV bus, where the HV bus voltage has the same scale of the battery cell voltage by using the HV bus voltage divided by the number of individual battery cells; first reduce the fuel cell power limit when the arbitrated measured voltage exceeds a first threshold to prevent over-voltage of the HV bus and/or the HV battery; and then reduce the regenerative braking power limit when the arbitrated measured voltage exceeds a second threshold, which is greater than the first threshold, to further prevent over-voltage of the HV bus and/or the HV battery.
2 . The FCEV of claim 1 , further comprising: a motor control processor in signal communication with the electric traction motor and the controller; a battery pack control module in signal communication with the HV battery and the controller; and a fuel cell processor in signal communication with the FCS and the controller.
3 . The FCEV of claim 1 , wherein the controller is further programmed to continuously arbitrate the measured voltage of the individual battery cells and the measured voltage of the HV bus.
4 . The FCEV of claim 3 , wherein the controller includes: a fuel cell power limit controller to control the fuel cell power limit of the FCS; and a regenerative brake power limit controller to control the regenerative braking power limit of the electric traction motor.
5 . The FCEV of claim 4 , wherein the fuel cell power limit controller and the regenerative brake power limit controller are propositional derivative (PD) controllers.
6 . The FCEV of claim 4 , wherein the fuel cell power limit controller is programmed to reduce the fuel cell power limit when the arbitrated measured voltage exceeds the first threshold.
7 . The FCEV of claim 6 , wherein the regenerative brake power limit controller is programmed to reduce the regenerative braking power limit when the arbitrated measured voltage exceeds the second threshold.
8 . The FCEV of claim 7 , wherein the fuel cell power limit is reduced to a minimum value before the regenerative braking power limit is reduced.
9 . A method of operating a powertrain control system to prevent over-voltage of a fuel cell electric vehicle (FCEV) having an electric traction motor, a high voltage (HV) battery system including a HV bus and a HV battery, a fuel cell stack (FCS), and a controller having one or more processors configured to control (i) a fuel cell power limit of the FCS and (ii) a regenerative braking power limit of the electric traction motor, the method comprising: measuring, by the controller, a voltage of individual battery cells of the HV battery; measuring, by the controller, a voltage of the HV bus; determining, by the controller, an arbitrated measured voltage, which is a maximum of the measured voltage of the individual battery cells and the measured voltage of the HV bus, where the HV bus voltage has the same scale of the battery cell voltage by using the HV bus voltage divided by the number of individual battery cells; reducing, by a fuel cell power limit controller, the fuel cell power limit when the arbitrated measured voltage exceeds a first threshold to prevent over-voltage of the HV bus and/or the HV battery; and reducing, by a regenerative brake power limit controller, the regenerative braking power limit when the arbitrated measured voltage exceeds a second threshold, which is greater than the first threshold, to further prevent over-voltage of the HV bus and/or the HV battery.
10 . The method of claim 9 , further comprising, by the controller, continuously arbitrating the measured voltage of the individual battery cells and the measured voltage of the HV bus.
11 . The method of claim 9 , wherein the fuel cell power limit is reduced to a minimum value before the regenerative braking power limit is reduced.
12 . The method of claim 9 , wherein the FCEV further includes: a motor control processor in signal communication with the electric traction motor and the controller; a battery pack control module in signal communication with the HV battery and the controller; and a fuel cell processor in signal communication with the FCS and the controller.
13 . A fuel cell electric vehicle (FCEV), comprising: an electric traction motor configured to drive the FCEV and generate power through regenerative braking; a regenerative brake power limit controller to control the regenerative braking power limit of the electric traction motor; a high voltage (HV) battery system including a HV bus and a HV battery configured to power the electric traction motor; a fuel cell stack (FCS) configured to generate electricity to recharge the HV battery and/or power the electric traction motor; a fuel cell power limit controller to control the fuel cell power limit of the FCS; and a powertrain control system for preventing over-voltage of the HV bus and HV battery, including a powertrain controller having one or more processors configured to control (i) a fuel cell power limit of the FCS via the fuel cell power limit controller, and (ii) a regenerative braking power limit of the electric traction motor via the regenerative brake power limit controller, wherein the powertrain controller is programmed to: measure (i) a voltage of individual battery cells of the HV battery and (ii) a voltage of the HV bus; continuously arbitrate the measured voltage of the individual battery cells and the measured voltage of the HV bus; determine an arbitrated measured voltage, which is a maximum of the measured voltage of the individual battery cells and the measured voltage of the HV bus, where the HV bus voltage has the same scale of the battery cell voltage by using the HV bus voltage divided by the number of individual battery cells; reduce, by the fuel cell power limit controller, the fuel cell power limit when the arbitrated measured voltage exceeds a first threshold; and reduce, by the regenerative brake power limit controller, the regenerative braking power limit when the arbitrated measured voltage exceeds a second threshold, which is greater than the first threshold, and wherein the fuel cell power limit is reduced to a minimum value before the regenerative braking power limit is reduced.

Description

FIELD The present application relates generally to hydrogen fuel cell electric vehicle control systems and, more particularly, to hydrogen fuel cell electric vehicle energy management control system to prevent over-voltage. BACKGROUND A hydrogen fuel cell electric vehicle typically includes a battery pack that can be charged via regenerative braking or a hydrogen fuel cell stack. However, either charging method can potentially result in over-charging of the battery pack, which may result in faults that cause the battery pack to open contactors to disconnect from the vehicle or powertrain to protect itself. Once the contactors are open, the vehicle will lose traction power. Additionally, over-voltage may also occur in the high voltage bus, causing the fuel cell DC/DC converter to shut down to protect itself. Under low state of charge driving conditions, this may potentially result in loss of traction power or degraded driving performance once the fuel cell DC/DC shuts down. Accordingly, while such conventional systems do work well for their intended purpose, there is a desire for improvement in the relevant art. SUMMARY In accordance with one example aspect of the invention, a fuel cell electric vehicle (FCEV) is provided. In one example implementation, the FCEV includes an electric traction motor configured to drive the FCEV and generate power through regenerative braking, a high voltage (HV) battery system including a HV bus and a HV battery configured to power the electric traction motor, and a fuel cell stack (FCS) configured to generate electricity to recharge the HV battery and/or power the electric traction motor. A powertrain control system for preventing over-voltage of the HV bus and HV battery includes a controller having one or more processors configured to control (i) a fuel cell power limit of the FCS, and (ii) a regenerative braking power limit of the electric traction motor. The controller is programmed to measure a voltage of the HV battery system, and selectively limit the fuel cell power limit and/or the regenerative braking power limit when the measure voltage exceeds a predetermined threshold. In addition to the foregoing, the described HEV may include one or more of the following features: wherein the controller is further programmed to measure (i) a voltage of individual battery cells of the HV battery and (ii) a voltage of the HV bus; wherein the controller is further programmed to continuously arbitrate the measured voltage of the individual battery cells and the measured voltage of the HV bus; and wherein the controller is further programmed to determine an arbitrated measured voltage, which is a maximum of the measured voltage of the individual battery cells and the measured voltage of the HV bus, where the HV bus voltage has the same scale of the battery cell voltage by using the HV bus voltage divided by the number of individual battery cells. In addition to the foregoing, the described HEV may include one or more of the following features: wherein the controller includes a fuel cell power limit controller to control the fuel cell power limit of the FCS, and a regenerative brake power limit controller to control the regenerative braking power limit of the electric traction motor; wherein the fuel cell power limit controller and the regenerative brake power limit controller are propositional derivative (PD) controllers; and wherein the fuel cell power limit controller is programmed to reduce the fuel cell power limit when the arbitrated measured voltage exceeds a first threshold. In addition to the foregoing, the described HEV may include one or more of the following features: wherein the regenerative brake power limit controller is programmed to reduce the regenerative braking power limit when the arbitrated measured voltage exceeds a second threshold, which is greater than the first threshold; wherein the fuel cell power limit is reduced to a minimum value before the regenerative braking power limit is reduced; and a motor control processor in signal communication with the electric traction motor and the controller, a battery pack control module in signal communication with the HV battery and the controller, and a fuel cell processor in signal communication with the FCS and the controller. In accordance with another example aspect of the invention, a method of operating a powertrain control system to prevent over-voltage of a fuel cell electric vehicle (FCEV) is provided. The FCEV includes an electric traction motor, a high voltage (HV) battery system including a HV bus and a HV battery, a fuel cell stack (FCS), and a controller having one or more processors configured to control (i) a fuel cell power limit of the FCS and (ii) a regenerative braking power limit of the electric traction motor. In one example implementation, the method includes measuring, by the controller, a voltage of the HV battery system, and selectively limiting, by the controller, the fuel cell power limit a