Patent Description:
In a traditional fuel cell system used for transportation propulsion, a battery is used to provide power output bursts required by the application. For example, in a typical automotive application, a response time of <NUM> is desired to human throttle inputs, which is an order of magnitude faster than the fastest fuel cell systems today. The gap is bridged by the battery system that is constantly connected to the fuel cell generator via a complex controllable DC to DC converter that manages power flow between the fuel cell and the battery, and then the battery is connected to the propulsive system via another complex power conversion system.

In such a configuration, typical voltages of the fuel cell system and the buffer battery are limited to <NUM>-250V due to the increasing cost and complexity of larger cell counts that would be required to support higher voltage. On the other hand, optimization of the propulsive part of the system (inverter + motor) demand higher voltages - typically <NUM>-700V in today's high- performance propulsive systems. Therefore, a typical fuel cell architecture today deploys a boost converter to bring the voltage from <NUM>-250V to <NUM>-700V. Such a high boost ratio results in significant electrical stresses for all the power conversion components and relatively low efficiency of conversion.

Additionally, the voltage levels of the fuel cell stack output can vary by more than 2x between the no-load and full rated load states. This creates additional complexity in power electronics design. The overall outcome is usually an expensive heavy system, wasting up to <NUM>% of the energy in heat output from power conversion electronics at maximum rated power.

<CIT> discloses a method of controlling dc/dc converter, method of controlling dc/dc converter apparatus, and method of controlling driving operation of electric vehicle.

<CIT> discloses an ultracapacitor based power storage device suitable for use in hybrid fuel cell systems and other power systems that includes circuitry for simulating the response of a battery.

This disclosure is directed to methods and systems that substantially obviate one or more of the above and other problems associated with conventional technology.

In accordance with one aspect, this disclosure is directed to an integrated fuel cell power delivery system. The system includes a first power source configured to supply power to a propulsion inverter, a second power source configured to supply power to the propulsion inverter, a disconnect operably connected to the second power source, a bypass diode operably connected to the first power source and/or the second power source, a sensor that detects an output voltage of the integrated fuel cell power system, a processor, and a memory. The bypass diode and the disconnect selectively provide power to the propulsion inverter by the first power source and/or the second power source. The memory includes instructions stored thereon, which when executed by the processor, cause the integrated fuel cell power system to access a signal from the sensor, determine if the accessed first signal is greater than a first threshold voltage, and operably disconnect an output of at least one of the first power source or the second power source to the integrated fuel cell power system by the disconnect based on the determination; and an electronic voltage limiting device (<NUM>) configured to selectively provide a load on at least one of the first power source or second power source; wherein the instructions, when executed by the processor, further cause the integrated fuel cell power system to: access the first signal from the sensor; determine if the accessed first signal is greater than a third threshold voltage; and selectively provide a load, by the electronic voltage limiting device, to at least one of the first power source or second power source based on the determination, wherein the voltage limiting device includes a calibrated load configured to load the output of the integrated fuel cell power system in a case where the output voltage exceeds the predetermined third threshold voltage.

In aspects, the instructions, when executed by the processor, may further cause the integrated fuel cell power system to access the first signal from the sensor, determine if the accessed first signal is less than a second threshold voltage, and operably connect the output of the second power source to the integrated fuel cell power system by the disconnect based on the determination.

In aspects, the first power source may include a fuel cell stack and/or a battery.

In aspects, the second power source may include a fuel cell stack and/or a battery.

In aspects, the electronic voltage limiting device may include a field-effect transistor (FET).

In aspects, the system may further include a cathode air compressor configured to be powered by the first power source and/or the second power source.

According to yet another aspect, the disclosure is directed to an integrated fuel cell power system including a first power source configured to supply power to a propulsion inverter, a second power source configured to supply power to the propulsion inverter, an electronic voltage limiting device configured to selectively provide a load on the first power source and/or second power source, a sensor that detects an output voltage of the integrated fuel cell power system, a processor, and a memory. The memory includes instructions stored thereon, which when executed by the processor, cause the integrated fuel cell power system to access a signal from the sensor, determine if the accessed first signal is greater than a threshold voltage, and selectively provide a load, by the electronic voltage limiting device, to the first power source and/or second power source based on the determination, wherein the voltage limiting device includes a calibrated load configured to load the output of the integrated fuel cell power system in a case where the output voltage exceeds the predetermined threshold.

In aspects, the voltage limiting device may include a field effect transistor (FET).

According to yet another aspect, the disclosure is directed to a computer-implemented method for integrated fuel cell stack and battery management including accessing a signal from a sensor, the sensor configured to detect an output voltage of a first power source and/or a second power source, either individually or in series, determining if the accessed sensor signal is greater than a first threshold voltage, and operably disconnecting the output of the second power source by a power source disconnect based on the determination. The power source disconnect is operably connected to the first power source and the second power source. A plurality of bypass diodes and the power source disconnect are configured to selectively provide power to a propulsion inverter by the first power source and/or the second power source, either individually or simultaneously, the method further comprising: accessing the first signal from the sensor; determining if the accessed first signal is greater than a third threshold voltage; and selectively providing a load, by an electronic voltage limiting device, to at least one of the first power source or second power source based on the determination, wherein the electronic voltage limiting device is configured to selectively provide a load on at least one of the first power source or second power source, wherein the voltage limiting device includes a calibrated load configured to load the output of the integrated fuel cell power system in a case where the output voltage exceeds the predetermined second threshold voltage.

In aspects, the method may further include accessing the signal from the sensor, determining if the accessed first signal is less than a second threshold voltage, and operably connecting the output of the second power source to the integrated fuel cell power system by the disconnects based on the determination.

In aspects, the first power source may include a fuel cell stack and/or a battery. The second power source may include a fuel cell stack and/or a battery.

In aspects, the voltage limiting device may include a field-effect transistor (FET).

Additional aspects related to this disclosure are set forth, in part, in the description which follows, and, in part, will be obvious from the description or may be learned by practice of this disclosure.

It is to be understood that both the foregoing and the following descriptions are exemplary and explanatory only and are not intended to limit the claimed disclosure or application thereof in any manner whatsoever.

The invention is defined by the features of the independent claims <NUM>, <NUM> and <NUM>.

The accompanying drawings, which are incorporated in and constitute a part of this specification, exemplify the aspects of the present disclosure and, together with the description, explain and illustrate the principles of this disclosure.

In the following detailed description, reference will be made to the accompanying drawing(s), in which identical functional elements are designated with like numerals. The accompanying drawings show by way of illustration, and not by way of limitation, specific aspects, and implementations consistent with principles of this disclosure.

Referring to <FIG>, the integrated fuel cell power delivery system <NUM> generally includes a first power source <NUM> (e.g., the fuel cell system <NUM> and/or battery <NUM>) connected substantially in series with a second power source <NUM>, with individual disconnects 108a, 108b, and with bypass diodes 116b, 116c allowing the power flow even when the battery <NUM> or the fuel cell system <NUM> is selectively disconnected by the power source disconnect 108a, 108b. High-quality bypass diodes 116b, 116c are inexpensive and light, and at typical 250V fuel cell stack (e.g., fuel cell system <NUM>) / battery <NUM> voltage levels, the bypass diodes 116b, 116c may result in only about <NUM>-<NUM>% losses in the system, compared to the state of the art system losses of up to about <NUM>%, with the corresponding improvement in the complexity and weight of cooling systems for such a powertrain. The integrated fuel cell power delivery system <NUM> may include a controller <NUM> (<FIG>).

The integrated fuel cell power delivery system <NUM>, may further include an isolated DC to DC converter configured to charge the battery <NUM> with excess power from the fuel cell system <NUM>.

Furthermore, the integrated fuel cell power delivery system <NUM> also contains an output voltage sensor <NUM>, an electronic voltage limiting device <NUM> (e.g., a field-effect transistor (FET)), that work together with the controller <NUM> to prevent overvoltage on the output of the integrated fuel cell power delivery system <NUM>. The electronic voltage limiting device <NUM> may include, for example, a calibrated load/power resistor that is designed to load the output of the integrated fuel cell power delivery system <NUM> if the output voltage of the integrated fuel cell power delivery system <NUM> exceeds a predetermined value. For example, the voltage sensor <NUM> may detect an output voltage of the integrated fuel cell power delivery system <NUM>, and the electronic voltage limiting device <NUM> may open above a source-drain voltage of about 790V and switch in the electronic voltage limiting device <NUM> (e.g., the calibrated load) to provide sufficient load on the fuel cell system <NUM> to avoid overvoltage of the output voltage of the of the integrated fuel cell power delivery system <NUM>, sufficient to manage most transient conditions (e.g., sudden load drop, before the controller <NUM> is able to reduce the fuel cell stack <NUM> and/or battery <NUM> output). Due to the typical characteristics of fuel cells, a relatively small load (e.g., <NUM>% of the max power rating of the fuel cell) will result in a very significant voltage drop relative to the open-circuit voltage of the output of the integrated fuel cell power delivery system <NUM>. The dissipated power across the load provided by the electronic voltage limiting device <NUM> can be redirected and used for useful purposes (e.g., heating of the passenger compartment, battery recharge, etc.).

Finally, the controller <NUM> reads the sensors, conducts necessary calculations, and produces commands delivered to the fuel cell system <NUM>, power source disconnects 108a, 108b, and the electronic voltage limiting device <NUM>.

In one or more aspects, the proposed connection approach for the battery <NUM> and fuel cell system <NUM> results in the output voltage high enough to operate the propulsive system without an intermediate booster, yet without a possibility of overvoltage.

For example, the controller <NUM> connects the battery <NUM> to the output of the integrated fuel cell power delivery system <NUM> only when the peak / high output power of the integrated fuel cell power delivery system <NUM> is required. An example of a perfect application is an aircraft powertrain, where peak power is needed only on takeoff, while in cruise, only <NUM>-<NUM>% of the peak power is required. In the case of such a power profile, the controller <NUM> connects the battery <NUM> into the circuit only for the takeoff and initial climb, producing full output voltage and power. Once the initial climb is complete, the power source disconnects the battery <NUM>, and the powertrain operates on just a fuel cell system <NUM> at a steady output equivalent to <NUM>-<NUM>% of the max system power rating.

The battery <NUM> can be optionally recharged from the fuel cell <NUM> via an isolated DC to DC converter <NUM>. Such DC to DC converter <NUM> would require a much lower power rating than the original booster converter and, therefore would be significantly cheaper and lighter. The overall system weight optimization can be achieved through balancing the battery <NUM> capacity (and therefore weight) and the converter power rating.

In aspects, a hydrogen fuel cell cathode air compressor <NUM> can be powered solely by battery power.

For instance, before hydrogen and oxygen are supplied to the anode and cathode of the hydrogen fuel cell system <NUM>, the cathode air compressor <NUM> can be powered to bring up the hydrogen fuel cell voltage before closing the system power source disconnect 108b (see <FIG>).

In aspects, the hydrogen fuel cell cathode air compressor <NUM> can be powered solely by the hydrogen fuel cell power while the system load is driven by the battery <NUM> and fuel cell system <NUM> in series.

For example, to reduce the energy required to recharge the battery <NUM>, the battery <NUM> may be bypassed with a single-pole double-throw relay <NUM> (controlled by controller <NUM>) on the positive end of the cathode air compressor <NUM> (<FIG>). Bypassing the battery <NUM> in this manner the power reserves of the system to be extended as much as possible (see <FIG>).

In aspects, the hydrogen fuel cell cathode air compressor <NUM> can be powered off the fuel cell system <NUM> and/or the rechargeable battery <NUM> in series.

For instance, to run the cathode air compressor <NUM> efficiently and at full power the cathode air compressor <NUM> can be driven on the combined battery <NUM> and fuel cell voltage of fuel cell system <NUM> using the integrated fuel cell power delivery system <NUM> detailed in <FIG>. By closing both the battery and power source disconnects 108a, 108b, and not bypassing the battery <NUM> with the double pole single throw relay <NUM>, the combined voltage may be supplied to the cathode air compressor <NUM> (see <FIG>).

In aspects, the hydrogen fuel cell cathode air compressor <NUM> can be started by the rechargeable battery <NUM> and transitioned to be run by the rechargeable battery <NUM> and fuel cell system <NUM> in series.

For example, the integrated fuel cell power delivery system <NUM> can start with the power source disconnect 108a open, effectively removing the fuel cell system <NUM> from the circuit, and allowing current to pass through the a bypass diode 116b, 116c. Power is applied to the cathode air compressor <NUM>, voltage is then present across the fuel cell system <NUM>, and then the power source disconnect 108a is closed to bring the integrated fuel cell power delivery system <NUM> to the full combined stack voltage (see <FIG>).

In aspects, the fuel cell system <NUM> can charge the rechargeable battery <NUM> via an isolated DC to DC converter <NUM>.

For example, when excess power is available from the fuel cell system <NUM>, the isolated DC to DC converter <NUM> can charge the battery <NUM> to extend the range of the integrated fuel cell power delivery system <NUM>. This is desirable because hydrogen has a significant energy density advantage over the currently available battery technologies (see <FIG>).

In aspects, the isolated DC to DC converter <NUM> may be configured to convert the approximately 300V fuel cell to an approximately 700V combined stack voltage if connected as an additive DC to DC converter.

In aspects, the electronic voltage limiting device <NUM> can be used such that the combined battery <NUM> and fuel cell system <NUM> output voltage cannot exceed a specified high voltage limit.

For instance, a power resistor and a FET opening above 790V source-drain voltage can be utilized to provide sufficient load on the fuel cell to avoid overvoltage of the output supply - sufficient to manage most transient situations (e.g., sudden load drop, before the controller <NUM> is able to reduce the fuel cell output).

In aspects, this disclosure describes a method to remove the battery <NUM> if the battery is no longer desirable.

For example, if the battery <NUM> is depleted or no longer desired, it can be taken out of the circuit by opening the power source disconnect 108a, 108b (see <FIG>). The integrated fuel cell power delivery system power will then flow through the battery bypass diode keeping the integrated fuel cell power delivery system <NUM> powered.

With reference to <FIG>, the fuel cell system <NUM> of integrated fuel cell power delivery system <NUM>, which may be circular, can be coaxially supported on elongated shaft (e.g., concentric, not shown) of a powertrain of an integrated hydrogen-electric engine system of an aircraft (not shown), such that air channels <NUM> of fuel cell system <NUM> may be oriented in parallel relation with elongated shaft (e.g., horizontally, or left-to-right). Fuel cell system <NUM> may be in the form of a proton-exchange membrane fuel cell (PEMFC). The fuel cells of the fuel cell system <NUM> are configured to convert chemical energy liberated during the electrochemical reaction of hydrogen and oxygen to electrical energy (e.g., direct current). Depleted air and water vapor are exhausted from fuel cell system <NUM>. The electrical energy generated from fuel cell system <NUM> is then transmitted to a motor assembly (not shown), which is also coaxially/concentrically supported on elongated shaft (not shown). In aspects, integrated fuel cell power delivery system <NUM> may include any number of external radiators (not shown) for facilitating airflow and adding, for instance, additional cooling. Notably, fuel cell system <NUM> can include liquid-cooled and/or air-cooled cell types so that cooling loads are integrated into heat exchangers (not shown) for reducing total amount of external radiators needed in the system.

In aspects, the fuel cell system <NUM> may include a fuel cell cathode air compressor <NUM> configured to supply air to the fuel cell system <NUM>, a hydrogen fuel source <NUM> configured to supply hydrogen to the fuel cell system <NUM>, and a hydrogen pressure regulating system <NUM> configured to regulate the hydrogen from the hydrogen fuel source <NUM> to the fuel cell system <NUM>.

Finally, the processes and techniques described herein are not inherently related to any particular apparatus and may be implemented by any suitable combination of components. Further, various types of general-purpose devices may be used in accordance with the teachings described herein. It may also prove advantageous to construct specialized apparatus to perform the method steps described herein. This disclosure has been described in relation to the examples, which are intended in all respects to be illustrative rather than restrictive.

<FIG> illustrates that controller <NUM> includes a processor <NUM> connected to a computer-readable storage medium or a memory <NUM>. The computer-readable storage medium or memory <NUM> may be a volatile type of memory, e.g., RAM, or a non-volatile type of memory, e.g., flash media, disk media, etc. In various aspects of the disclosure, the processor <NUM> may be another type of processor such as, without limitation, a digital signal processor, a microprocessor, an ASIC, a graphics processing unit (GPU), a field-programmable gate array (FPGA), or a central processing unit (CPU). In certain aspects of the disclosure, network inference may also be accomplished in systems that have weights implemented as memristors, chemically, or other inference calculations, as opposed to processors.

In aspects of the disclosure, the memory <NUM> can be random access memory, read-only memory, magnetic disk memory, solid-state memory, optical disc memory, and/or another type of memory. In some aspects of the disclosure, the memory <NUM> can be separate from the controller <NUM> and can communicate with the processor <NUM> through communication buses of a circuit board and/or through communication cables such as serial ATA cables or other types of cables. The memory <NUM> includes computer-readable instructions that are executable by the processor <NUM> to operate the controller <NUM>. In other aspects of the disclosure, the controller <NUM> may include a network interface <NUM> to communicate with other computers or to a server. A storage device <NUM> may be used for storing data.

The disclosed method may run on the controller <NUM> or on a user device, including, for example, on a mobile device, an IoT device, or a server system. The controller <NUM> is configured to receive among other data, the fuel supply status, aircraft location, and control, among other features, the pumps, motors, sensors, etc..

Further, as can be appreciated, the integrated hydrogen-electric engine system <NUM> can include any number and/or type of sensors, electrical components, and/or telemetry devices that are operatively coupled to controller <NUM> for facilitating the control, operation, and/or input/out of the various components of integrated hydrogen-electric engine system <NUM> for improving efficiencies and/or determining errors and/or failures of the various components.

Referring to <FIG>, there is shown a flow chart of an exemplary computer-implemented method <NUM> for integrated fuel cell stack and battery management in accordance with aspects of the present disclosure. Although the steps of <FIG> are shown in a particular order, the steps need not all be performed in the specified order, and certain steps can be performed in another order. For simplicity, <FIG> will be described below, with the controller <NUM> performing the operations. However, in various aspects, the operations of <FIG> may be performed in part by the controller <NUM> of <FIG> and in part by another device, such as a remote server. These variations are contemplated to be within the scope of the present disclosure.

Initially, at step <NUM>, the controller <NUM> accesses a signal from a sensor configured to detect an output voltage of a first power source <NUM> or a second power source <NUM> (either individually or in series) of the integrated fuel cell power delivery system <NUM> of <FIG>.

The first power source <NUM> and/or the second power source <NUM> may include any combination of fuel cell systems <NUM> and/or batteries <NUM>. For example, the first power source <NUM> may include a fuel cell system <NUM>, and the second power source <NUM> may include the battery <NUM>.

Next, at step <NUM>, the controller <NUM> determines if the accessed sensor signal is greater than a first threshold voltage (e.g., about 750Volts).

Next, at step <NUM>, the controller <NUM> operably disconnects an output of the second power source <NUM> by the power source disconnect(s) 108a, 108b, based on the determination that sensed voltage is greater than the first threshold voltage. For example, if the sensed voltage measures about <NUM> Volts, then the controller would determine that this is greater than the threshold of about <NUM> Volts and would disconnect the power source disconnect(s) 108a, 108b, to disconnect the output of the second power source <NUM> to reduce the system output voltage. The power source disconnect(s) 108a, 108b, may be operably connected to the first power source and/or the second power source <NUM>. The plurality of bypass diodes 116b and 116c and the power source disconnect(s) 108a, 108b, are configured to selectively provide power to a propulsion inverter <NUM> by at least one of the first power source <NUM> or the second power source <NUM>, either individually or simultaneously.

In aspects, the first power source <NUM> and/or the second power source <NUM> may power the cathode air compressor <NUM>, which is operably connected to outputs of the integrated fuel cell power system <NUM>.

In aspects, the controller <NUM> may determine if the accessed first signal is less than a second threshold voltage. In aspects, the controller <NUM> may operably connect the output of the second power source <NUM> to the integrated fuel cell power system <NUM> by the disconnects based on the determination. For example, if the sensed voltage is about <NUM> volts and the second threshold voltage is about <NUM> volts, then the controller <NUM> would operably connect the output of the second power source <NUM> to the integrated fuel cell power system <NUM>.

In aspects, at step <NUM>, the controller <NUM> may determine if the accessed first signal is greater than a third threshold voltage (e.g., about 725Volts). Next, at step <NUM>, the controller <NUM> selectively provides a load, by an electronic voltage limiting device <NUM>, to the first power source and/or second power source based on the determination the sensed voltage is greater than the third threshold voltage. The electronic voltage limiting device <NUM> is configured to selectively provide a load on at least one of the first power source <NUM> and/or second power source <NUM>.

Claim 1:
An integrated fuel cell power delivery system (<NUM>), the system comprising:
a first power source (<NUM>) configured to supply power to a propulsion inverter (<NUM>);
a second power source (<NUM>) configured to supply power to the propulsion inverter;
a disconnect (108b) operably connected to the second power source;
a bypass diode (116b) operably connected to the first power source and the second power source, wherein the bypass diode and the disconnect selectively provides power to the propulsion inverter by at least one of the first power source or the second power source;
a sensor (<NUM>) that detects an output voltage output by the integrated fuel cell power system;
a processor;
a memory, which includes instructions stored thereon, which when executed by the processor, cause the integrated fuel cell power system to:
access a first signal from the sensor;
determine if the accessed first signal is greater than a first threshold voltage; and
operably disconnect an output of at least one of the first power source or the second power source to the integrated fuel cell power system by the disconnect based on the determination; and
an electronic voltage limiting device (<NUM>) configured to selectively provide a load on at least one of the first power source or second power source;
wherein the instructions, when executed by the processor, further cause the integrated fuel cell power system to:
access the first signal from the sensor;
determine if the accessed first signal is greater than a third threshold voltage; and
selectively provide a load, by the electronic voltage limiting device, to at least one of the first power source or second power source based on the determination,
wherein the voltage limiting device includes a calibrated load configured to load the output of the integrated fuel cell power system in a case where the output voltage exceeds the predetermined third threshold voltage.