Abstract: An electrified vehicle include a chassis, a front axle coupled to the chassis, a rear axle coupled to the chassis, an electric motor supported by the chassis, and a trailer coupled to a rear end of the chassis and configured to be towed by the electrified vehicle. The electric motor is configured to drive at least one of the front axle, the rear axle, or a component of the electrified vehicle. The trailer includes a trailer frame, a trailer axle coupled to the trailer frame, and an energy storage device supported by the trailer frame. The energy storage device includes a plurality of batteries. The energy storage device configured to power the electric motor.

Abstract: A concrete mixer truck includes a chassis, a plurality of tractive assemblies coupled to the chassis, a mixing drum rotatably coupled to the chassis, the mixing drum defining an internal volume configured to contain material and an aperture through which the material can enter and exit the internal volume, an energy storage device positioned at a rear end of the chassis and configured to provide electrical energy, and an electromagnetic device electrically coupled to the energy storage device, where the electromagnetic device is configured to receive the electrical energy from the energy storage device and provide mechanical energy to drive at least one of the plurality of tractive assemblies to propel the concrete mixer truck.

Abstract: A concrete mixer vehicle includes a chassis, a tractive assembly coupled to the chassis and configured to propel the concrete mixer vehicle, a mixing drum rotatably coupled to the chassis, and an electromagnetic device configured to convert electrical energy to mechanical energy to drive the tractive assembly. In a first configuration, a first battery module is removably coupled to the chassis and configured to provide the electrical energy to the electromagnetic device, and in a second configuration, the first battery module is removed from the chassis and replaced with a second battery module, the second battery module removably coupled to the chassis and configured to provide the electrical energy to the electromagnetic device.

Abstract: A system and method for operating a fuel cell stack of a fuel cell system in a vehicle when an error in cathode air flow rate is detected. The system and method include estimating a cathode air flow rate and detecting an error in the estimated cathode air flow rate. The system and method also include utilizing high frequency resistance measurements from a high frequency resistance sensor to control a relative humidity of the fuel cell stack when the error in the estimated cathode air flow rate has been detected.

Abstract: A system and method for operating a fuel cell stack of a fuel cell system in a vehicle when an error in cathode air flow rate is detected. The system and method include estimating a cathode air flow rate and detecting an error in the estimated cathode air flow rate. The system and method also include utilizing high frequency resistance measurements from a high frequency resistance sensor to control a relative humidity of the fuel cell stack when the error in the estimated cathode air flow rate has been detected.

Abstract: A system and method for controlling a fuel cell system start time based on various vehicle parameters. The method includes providing a plurality of inputs that identify operating conditions of the fuel cell system and determining a maximum allowable start-time of the fuel cell system using a hybridization control strategy and the plurality of inputs. The method then determines a maximum compressor speed and ramp rate to provide the optimal allowable start-time of the fuel cell system minimizing energy consumption and noise.

Abstract: A system and method for determining the maximum allowed stack current limit rate for a fuel cell stack that considers cell voltage. The method includes estimating a fuel cell stack voltage based on a fuel cell resistance value, stack variables and a current request signal. The fuel cell resistance value can be modeled based on stack temperature and stack relative humidity. The stack variables can include exchange current density and mass transfer coefficient. The method then uses the estimated fuel cell voltage and a look-up table based on estimated voltage to determine a current rate limit value for changing the current of the stack. The method then adds the current rate limit value and the current request signal to obtain the current set-point.

Abstract: A system and method for determining a loss of cooling fluid from a thermal sub-system in a fuel cell system. The method includes monitoring current feedback from a high temperature pump that pumps the cooling fluid through a coolant loop. A measured current from the pump is compared to an expected current for the system operating conditions, and if that current is significantly less than what is expected, then it may be as a result of low cooling fluid. If the measured current is less than the expected current for a predetermined period of time, then the system can take mitigating action as a result of a low cooling fluid. Further, if the pump speed is too low to provide an accurate current measurement, then it can be increased if an overflow tank level sensor indicates a low cooling fluid level.

Abstract: A method of estimating water vapor transfer unit degradation without having to remove the unit from a fuel cell system to which it cooperates, and a device performing the same. The method includes using a combination of a backward-looking model and a forward-looking model. The first of these models is used to evaluate changes in water vapor transfer effectiveness in the unit, while the second is for determining the water transfer rate of the unit. Together, the models provide a more accurate way to estimate and control relative humidity for both stack inlet and outlet flowpaths, as well as provide an indication of when service or replacement of the water vapor transfer unit may be warranted.

Abstract: A method for determining whether a fuel cell stack cooling fluid is flowing at cold fuel cell system start-up. The method monitors the temperature of the cooling fluid outside of the fuel cell stack, and determines whether the temperature of the cooling fluid is increasing properly as the temperature of the stack increases.

Abstract: A system and method for determining a loss of cooling fluid from a thermal sub-system in a fuel cell system. The method includes monitoring current feedback from a high temperature pump that pumps the cooling fluid through a coolant loop. A measured current from the pump is compared to an expected current for the system operating conditions, and if that current is significantly less than what is expected, then it may be as a result of low cooling fluid. If the measured current is less than the expected current for a predetermined period of time, then the system can take mitigating action as a result of a low cooling fluid. Further, if the pump speed is too low to provide an accurate current measurement, then it can be increased if an overflow tank level sensor indicates a low cooling fluid level.

Abstract: A method for improving fuel cell system reliability in the event of end cell heater failure in a fuel cell stack. The method includes detecting that an end cell heater has failed. If an end cell heater failure is detected, then the method performs one or more of setting a cooling fluid pump to a predetermined speed that drives a cooling fluid through cooling fluid flow channels in the fuel cell stack, limiting the output power of the fuel cell stack or the net power of the fuel cell system, limiting the maximum temperature of the cooling fluid flowing out of the stack, turning off stack anti-flooding algorithms that may be used to remove water from reactant gas flow channels in the stack, and turning off cathode stoichiometry adjustments for relative humidity control in response to water accumulating in cathode flow channels in the fuel cell stack.

Abstract: A method for performing a plausibility check of a fuel cell stack anode side pressure sensor to determine whether the pressure sensor is providing an accurate measurement. Prior to system start-up when a cathode side compressor is not providing cathode air to a fuel cell stack, and the cathode side of the stack is at ambient pressure, a pressure measurement from a differential pressure sensor between the anode side and the cathode side of the fuel cell stack is provided. The differential pressure sensor reading is added to a pressure measurement from an ambient pressure sensor, where the sum should be about the same as the pressure measurement from the anode side pressure sensor if the anode side pressure sensor is operating properly.

Abstract: A method for determining whether a fuel cell stack cooling fluid is flowing at cold fuel cell system start-up. The method monitors the temperature of the cooling fluid outside of the fuel cell stack, and determines whether the temperature of the cooling fluid is increasing properly as the temperature of the stack increases.

Abstract: A system and method for determining the maximum allowed stack current limit rate for a fuel cell stack that considers cell voltage. The method includes estimating a fuel cell stack voltage based on a fuel cell resistance value, stack variables and a current request signal. The fuel cell resistance value can be modeled based on stack temperature and stack relative humidity. The stack variables can include exchange current density and mass transfer coefficient. The method then uses the estimated fuel cell voltage and a look-up table based on estimated voltage to determine a current rate limit value for changing the current of the stack. The method then adds the current rate limit value and the current request signal to obtain the current set-point.

Abstract: A method for performing a plausibility check of a fuel cell stack anode side pressure sensor to determine whether the pressure sensor is providing an accurate measurement. Prior to system start-up when a cathode side compressor is not providing cathode air to a fuel cell stack, and the cathode side of the stack is at ambient pressure, a pressure measurement from a differential pressure sensor between the anode side and the cathode side of the fuel cell stack is provided. The differential pressure sensor reading is added to a pressure measurement from an ambient pressure sensor, where the sum should be about the same as the pressure measurement from the anode side pressure sensor if the anode side pressure sensor is operating properly.

Abstract: A method for improving fuel cell system reliability in the event of end cell heater failure in a fuel cell stack. The method includes detecting that an end cell heater has failed. If an end cell heater failure is detected, then the method performs one or more of setting a cooling fluid pump to a predetermined speed that drives a cooling fluid through cooling fluid flow channels in the fuel cell stack, limiting the output power of the fuel cell stack or the net power of the fuel cell system, limiting the maximum temperature of the cooling fluid flowing out of the stack, turning off stack anti-flooding algorithms that may be used to remove water from reactant gas flow channels in the stack, and turning off cathode stoichiometry adjustments for relative humidity control in response to water accumulating in cathode flow channels in the fuel cell stack.

Abstract: A vehicle cab noise suppressing system includes a cab interior panel having an opening exposed to acoustic noise in the cab, an acoustic resonator chamber, and a conduit communicating the resonator chamber to the opening. The resonator chamber is formed by a plurality of walls which are spaced apart from the interior panel and which are formed by a second panel. A third panel cooperates with the walls to enclose the resonator chamber. The chamber volume and the diameter and length of the conduit are chosen so as to acoustically tune the chamber to a noise frequency in the cab and thereby reduce noise in the cab.