Methods and systems for using a low voltage battery with a high voltage electric motor

Abstract

High voltage battery systems used on boats have a complicated production process, a high cost, and require various safety measurements. In order to reduce the complexity of required safety systems, one option is to decrease the battery voltage. In addition, by using a DC-DC converter, a high voltage electric motor can be used with low voltage batteries. The system can have the benefits of low voltage batteries such as lower cost, less insulation required, and a less complicated safety system, as well as having the benefits of high voltage electric motors like high efficiency and reduced size. The low voltage is boosted within the system to various higher voltage levels and thus allowing complex safety systems to be installed only in certain parts on the boat.

Description

[0001] METHODS AND SYSTEMS FOR USING A LOW VOLTAGE BATTERY WITH A HIGH VOLTAGE ELECTRIC MOTOR

[0002] BACKGROUND

[0003] Electric propulsion systems often use high voltage battery systems to achieve high efficiency and to allow for a smaller motor size. However, using high voltage batteries has several disadvantages such as preheating, high operating temperature, advanced safety, advanced isolation, and charging devices which are required when utilizing such battery powered systems.

[0004] High voltage batteries should be extensively tested during several stages of production. The development of such batteries includes different stages such as creating prototypes, experimenting models, design and product verification, and various certifications. All of these factors increase the batteries’ cost. On the other hand, the production of low voltage batteries is much less dangerous, and the safety requirements are nominal compared with high voltage batteries. Low voltage batteries are more popular, easier to install, and cost much less while still having advanced battery management systems.

[0005] The present disclosure introduces a method and a system for using low voltage batteries (48V, for example) with a high voltage electric drive train on a marine vehicle. The system includes high voltage insulation only for the motor and invertor system, since the low battery voltage battery has less of an insulation requirement. Due to the popularity of low voltage batteries, their management systems are well established and provide higher safety to the system users. In the systems of the present disclosure, the motor used to operate is a high voltage electric motor. Thus, the overall system is in general safer due to minimized risk of electrical safety concerns. BRIEF SUMMARY

[0006] High voltage battery systems used on boats have a complicated production process, a high cost, and require various safety measurements. In order to reduce the complexity of required safety systems while getting the benefits of the High voltage electric motor, one option in to decrease the battery voltage. In an exemplary system of the present disclosure, by using a DC- DC converter, a high voltage electric motor can be used with low voltage batteries. The system can have the benefits of low voltage batteries such as lower cost, less insulation required, and a less complicated safety system, as well as having the benefits of high voltage electric motors like high efficiency and reduced size. The low voltage is boosted within the system to various higher voltage levels and thus allowing complex safety systems to be installed only in certain parts on the boat. The DC-DC converter boosts a low voltage of the one or more batteries to power the high voltage electric motor.

[0007] In an exemplary system for using a low voltage battery on a boat of the present disclosure, the system comprises one or more low voltage electric batteries, a DC-DC converter in communication with each battery of the one or more batteries, a motor drive circuit in communication with each DC-DC converter, and a high voltage electric motor in communication with the motor drive circuit.

[0008] In an exemplary system for using a low voltage battery on a boat of the present disclosure, the DC-DC converter boosts a low voltage of the one or more batteries from a low voltage of 48V to a high voltage of 350-400V).

[0009] In an exemplary system for using a low voltage battery on a boat of the present disclosure, the DC-DC converter boosts a low voltage of the one or more batteries to power the high voltage electric motor. In an exemplary system for using a low voltage battery on a boat of the present disclosure, the system has less insulation requirements as compared to a system using one or more high voltage batteries instead of the one or more low voltage batteries.

[0010] In an exemplary system for using a low voltage battery on a boat of the present disclosure, the system has a more advanced battery management system as compared to a system using one or more high voltage batteries instead of the one or more low voltage batteries.

[0011] In an exemplary system for using a low voltage battery on a boat of the present disclosure, the system operates at a higher efficiency as compared to a system using a low voltage electric motor instead of the high voltage electric motor.

[0012] In an exemplary system for using a low voltage battery on a boat of the present disclosure, the system further comprises a bidirectional AC-DC converter, wherein the DC-DC converter is configured to use its bidirectional functionality to charge the system from an AC charger in communication with the bidirectional AC-DC converter.

[0013] In an exemplary system for using a low voltage battery on a boat of the present disclosure, the bidirectional AC-DC converter is configured to provide power from the system to an external load.

[0014] In an exemplary system for using a low voltage battery on a boat of the present disclosure, the DC-DC converter is bidirectional, and a high voltage charger is used to charge the system using a high voltage DC-link.

[0015] In an exemplary system for using a low voltage battery on a boat of the present disclosure, a voltage of the DC-DC converter is slightly boosted to be less than 60V. In an exemplary system for using a low voltage battery on a boat of the present disclosure, a voltage of the DC-DC converter is slightly boosted to be 59.8V so that the system can be considered to be a low voltage system.

[0016] In an exemplary system for using a low voltage battery on a boat of the present disclosure, less insulation and safety requirement is required as compared to a system having a DC-DC voltage of above 60V.

[0017] In an exemplary system for using a low voltage battery on a boat of the present disclosure, each DC-DC converter in communication with each battery of the one or more low voltage electric batteries supplies power to the high voltage electric motor.

[0018] BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The disclosed embodiments and other features, advantages, and disclosures contained herein, and the matter of attaining them, will become apparent and the present disclosure will be better understood by reference to the following description of the present disclosure taken in conjunction with the accompanying drawings, wherein:

[0020] FIG. 1 illustrates a schematic diagram of a boat’s electric drive system using a low voltage battery with a high voltage electric motor, according to at least one exemplary embodiment of the present disclosure;

[0021] FIG. 2 illustrates a schematic diagram of a boat’s electric drive system using a low voltage battery with a high voltage electric motor and an AC power source, according to at least one exemplary embodiment of the present disclosure; FIG. 3 illustrates a schematic diagram of a boat’s electric drive system using a low voltage battery with a high voltage electric motor and a DC power source, according to at least one exemplary embodiment of the present disclosure;

[0022] FIG. 4 illustrates a schematic diagram of a boat’s electric drive system using a low voltage battery with a low voltage electric motor, according to at least one exemplary embodiment of the present disclosure;

[0023] FIG. 5 illustrates a schematic diagram of a boat’s electric drive system using a low voltage battery with a high voltage electric motor using multiple DC-DC converters, according to at least one exemplary embodiment of the present disclosure.

[0024] As such, an overview of the features, functions and / or configurations of the components depicted in the figures will now be presented. It should be appreciated that not all of the features of the components of the figures are necessarily described and some of these non-discussed features (as well as discussed features) are inherent from the figures themselves. Other nondiscussed features may be inherent in component geometry and / or configuration. Furthermore, wherever feasible and convenient, like reference numerals are used in the figures and the description to refer to the same or like parts or steps. The figures are in a simplified form and not to precise scale.

[0025] DETAILED DESCRIPTION

[0026] For the purposes of promoting an understanding the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of this disclosure is thereby intended. Boats or watercrafts in general are normally used for various applications such as transportation, crafting, fishing, or just for leisure. However, the high voltage batteries used in existing systems require several safety systems, having complicated manufacturing procedures that are quite expensive. Because of the advanced systems, more and more safety and insulation methods are required for such systems.

[0027] The present disclosure includes disclosure of a method and a system for the use of low voltage batteries with a high voltage electric motor on a boat. On one side, low voltage batteries are much cheaper and more common than high voltage batteries, and therefore they are more popular. On the other hand, systems operating a high voltage electric drive system are more common and feature smaller power supply currents. At the same time, high voltage battery systems require complex safety and insulation systems. The proposed systems 100 of the present disclosure consist of a low voltage battery pack 101 (48V, for example) one or several connected in parallel, a DC-DC converter 102 to boost the low voltage into higher values, a motor drive circuit 103, and a high voltage electric motor 104, such as shown in Fig. 1. The DC-DC converter 102 boosts the low voltage (e.g. 48V) of the electric battery to higher voltage values (350V-400V, for example). This system is advantageous as the motor and drive portion of the boat could be small and only the motor area inside the boat has a high voltage; thus less safety systems are required for the battery side.

[0028] In at least one embodiment of the present disclosure, where the low voltage is boosted to high voltage (e.g. to 350V-400V or to 750V-850V), an AC-DC power supply module is added as shown in Fig. 2. The AC source 106 can charge the system 100 going through the bidirectional AC-DC converter 105 while the same AC-DC converter 105 can supply power from the battery 101 to a load in the opposite direction. In this case, the DC-DC converter 102 is also bidirectional to allow the power flow from and to the battery 101.

[0029] Also, in at least one embodiment of the present disclosure, a direct connection from the system 100 on the previous embodiments to high voltage DC source (HV charger) 107 can be used as shown in Fig. 3. The HV charger 107 can charge the batteries 101 and provide a fastcharging advantage to the system 100.

[0030] In at least one embodiment of the present disclosure, the DC-DC converter 102 boosts the low voltage at the battery 101 to a slightly higher voltage (around 59.8V), which is below 60V, such as shown in Fig. 4. By that, the whole system 100 is using low voltage with the benefits of higher safety and less insulation requirements, but sacrifices the high efficiency associated with high voltage electric motors.

[0031] Fig. 5 shows another embodiment of the current invention where each battery pack 101 or a number of battery packs 101 connected together has its own DC-DC converter 102, such as shown in Fig. 5. Each battery 101 with its DC-DC converter 102 contributes to powering the high voltage electric motor 104. Therefore, the DC-DC converter 102 rating can be reduced as well as the single battery 101 currents.

[0032] In each embodiment, the low voltage from the low voltage battery 101 is boosted up, the complex insulation and safety systems are required only in certain parts on the boat which involve the electric motor and its drive, enabling the use of lower cost batteries 101, drive circuits, and motors 104.

[0033] While various embodiments of devices, systems and methods for using the same have been described in considerable detail herein, the embodiments are merely offered as non-limiting examples of the disclosure described herein. It will therefore be understood that various changes and modifications may be made, and equivalents may be substituted for elements thereof, without departing from the scope of the present disclosure. The present disclosure is not intended to be exhaustive or limiting with respect to the content thereof.

[0034] Further, in describing representative embodiments, the present disclosure may have presented a method and / or a process as a particular sequence of steps. However, to the extent that the method or process does not rely on the particular order of steps set forth therein, the method or process should not be limited to the particular sequence of steps described, as other sequences of steps may be possible. Therefore, the particular order of the steps disclosed herein should not be construed as limitations of the present disclosure. In addition, disclosure directed to a method and / or process should not be limited to the performance of their steps in the order written. Such sequences may be varied and still remain within the scope of the present disclosure.

Claims

CLAIMS1. A system for using a low voltage battery on a boat, comprising: one or more low voltage electric batteries; a DC-DC converter in communication with each battery of the one or more batteries; a motor drive circuit in communication with each DC-DC converter; and a high voltage electric motor in communication with the motor drive circuit.

2. The system of claim 1 , wherein the DC-DC converter boosts a low voltage of the one or more batteries from a low voltage of 48V to a high voltage of 350-400V).

3. The system of claim 2, wherein the DC-DC converter boosts a low voltage of the one or more batteries to power the high voltage electric motor.

4. The system of claim 1, wherein the system has less insulation requirements as compared to a system using one or more high voltage batteries instead of the one or more low voltage batteries.

5. The system of claim 1, wherein the system has a more advanced battery management system as compared to a system using one or more high voltage batteries instead of the one or more low voltage batteries.

6. The system of claim 1, wherein the system operates at a higher efficiency as compared to a system using a low voltage electric motor instead of the high voltage electric motor.

7. The system of claim 1, further comprising: a bidirectional AC-DC converter, wherein the DC-DC converter is configured to use its bidirectional functionality to charge the system from an AC charger in communication with the bidirectional AC-DC converter.

8. The system of claim 7, wherein the bidirectional AC-DC converter is configured to provide power from the system to an external load.

9. The system of claim 1, wherein the DC-DC converter is bidirectional, and a high voltage charger is used to charge the system using a high voltage DC-link.

10. The system of claim 1, wherein a voltage of the DC-DC converter is slightly boosted to be less than 60V so that the system can be considered to be a low voltage system.

11. The system of claim 1, wherein a voltage of the DC-DC converter is slightly boosted to be 59.8V so that the system can be considered to be a low voltage system.

12. The system of claim 10, wherein less insulation and safety requirement is required as compared to a system having a DC-DC voltage of above 60V.

13. The system of claim 1, wherein each battery of the one or more low voltage electric batteries is in communication with one DC-DC converter to supplies power to the high voltage electric motor.

14. The system of claim 1, wherein each DC-DC converter in communication with each battery of the one or more low voltage electric batteries supplies power to the high voltage electric motor.

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