INTEGRATED MOTOR DRIVE AND BATTERY CHARGING SYSTEM
In one possible embodiment, a motor charging system for connection with a battery is provided having a rotor and a stator. The stator has delta H-bridge connected windings. The delta H-bridge includes an inverter at one side and a switching means at another side with each winding being connected between inverter pole switches and switching means pole switches. An A/C power port is connected to the windings such that when the switching means is off the A/C power port is connected to the battery bus via the windings and the inverter.
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The present application is a divisional of U.S. patent application Ser. No. 13/474,415, filed on May 17, 2012, by Rippel et al., entitled INTEGRATED MOTOR DRIVE AND BATTERY CHARGING SYSTEM, which is a continuation of PCT Application number PCT/US2010/057057, by Rippel et al., entitled INTEGRATED MOTOR DRIVE AND BATTERY CHARGING SYSTEM, filed Nov. 17, 2010, both herein incorporated by reference in their entireties, which claims priority of U.S. Provisional Application No. 61/262,117, by Rippel et al., filed Nov. 17, 2009, herein incorporated by reference in its entirety.
BACKGROUNDElectric motors and charging systems for vehicles need to be light weight, compact, and convenient. Induction motors are often used in vehicles. A separate inverter charging system is used to charge the battery from a utility power line, such as a 220 VAC wall socket.
In this system 100, the battery 105 is charged by a separate AC to DC charger 110, which is connected to utility power 115. The charger 110 is connected across the battery 105.
With such a system, the charger 110 adds additional weight to the vehicle if integrated or separately carried on board the vehicle. If separate from the vehicle, the charger 110 might not be present, in the event it is needed for convenience or opportunity charging, or in case of an emergency.
What is needed is a charging system for electric vehicles that is light weight and convenient.
SUMMARYIn one possible embodiment, a motor charging system for connection with a battery is provided having a rotor and a stator. The stator has Y-connected windings connected together connected at a neutral node. An inverter is connected between a battery bus and the stator windings. Switches are connected in the windings so as to be capable of disconnecting two of the windings from the neutral node and connecting the two windings to a single phase A/C power connector.
In an alternate embodiment, a motor charging system for connection with a battery is provided having a rotor and a stator. The stator has delta H-bridge connected windings. The delta H-bridge includes an inverter at one side and a switching means at another side with each winding being connected between inverter pole switches and switching means pole switches. An A/C power port is connected to the windings such that when the switching means is off the A/C power port is connected to the battery bus via the windings and the inverter.
Various embodiments may include interphase transformers.
The features and advantages of the present invention will be better understood with regard to the following description, appended claims, and accompanying drawings where:
In various embodiments, a battery/motor drive with integrated recharge is provided. The motor may be any three-phase machine including induction and DC brushless. The recharge source may be single phase, three phase, or DC, with any voltage level, preferably a voltage level such that the peak voltage is less than the battery voltage Vbat. In various embodiments, any power factor can be provided, including 1 and −1 (unity power factor for reverse power flow). Some advantages of various embodiments include, reduced DC bus ripple current, reduced phase ripple current, elimination of phase contactor, and elimination of the winding neutral splice within the machine.
Open Y Configuration (FIG. 2)In
In various embodiments, the controller 270 monitors the utility voltage and controls current in the windings 220 so as to track the AC voltage so as to end up with unity power factor. Another function of the controller 270 is to monitor current to the battery 205 and battery 205 voltage to regulate the current going into battery 205 and/or at some point switch to regulate voltage into battery 205 and reduce current into battery 205.
During charging, the rotor 240 may be locked or otherwise secured. During motor operation, the switch 210 is switched so that the windings 220a, 220b, and 220c are Y-connected, disconnecting the utility power 215 from the winding 220. The utility power 215, and optionally in some embodiments the EMI filter 212, may be physically disconnected from the circuit 200.
Open Delta H-Bridge Configuration (FIGS. 3-5)In the motoring mode, the switches 450x and 450y are operated symmetrically. In the recharge mode, the switches 450y are held off.
It is understood that in various embodiments, the utility power 415, and in some embodiments (not shown) the recharge filter 412, may be plugged/unplugged from the circuit 400 for charging/motoring. Thus, it is likely wise to place recharge switches 410 in series with the recharge port 414. This provides added safety. The optional recharge switches 410 may be utilized to connect the utility power 415 via the optional recharge filter 412 during recharge (or when generating DC power at the port 414).
An advantage of some embodiments of the open delta H-bridge configuration is the phase ripple fundamental frequency is 2f and peak amplitude at ripple/peak modulation voltage is equal to 1. This compares with 1.15 for conventional. Thus, high frequency AC losses in some winding embodiments are reduced by 30%. Fundamental ripple on bus capacitor 407 is increased from 2f to 4f and ripple magnitude is reduced by a factor of 2*sqrt3.
In some embodiments, the switches 450x may be replaced each with sub phases and interphase transformers to provide further ripple attenuation. This may be desired in some embodiments, so that the recharge filter 412 can be down sized.
In recharge mode, harmonic cancelation by the interphase transformers 525a-c is such that the lowest harmonics are at 6f with a voltage reduction of 3 times as compared to the circuit 400 of
Furthermore, phase-to-phase capacitors 513 on the order of 10 microFarads and 100 microFarads across the utility power lines may be added to provided improved harmonic cancelation. Thus, various embodiments have a great advantage in that they have relatively low ripple and a relatively small filter capacitance. This is especially true where the motor is large and the stator inductance Ls is small.
Typically, in the various embodiments, a port 514 is provided for connection to utility power (not shown in
Although in the circuit shown in
With various embodiments in accordance with the open delta h-bridge configuration, the recharge power rating may be reduced by 1/sqrt3 relative to a three phase Y-connected circuit. On the other hand, a benefit is that at the reduced power, where most of the recharge energy will flow, the magnetic losses are greatly reduced. With ΔB reduced by 1/(2*sqrt3) and f increased 2 times, the magnetic losses will be reduced by more than 3 times.
In various embodiments, charging through the windings may present problems which can include capacitance between winding and case of motor. Common mode currents can be generated in that coupling. One solution is to isolate the motor from the vehicle to prevent currents on the frame of the vehicle, which could cause shock hazard. This may also include a non-conducting mounting and a non-conducting motor shaft, or coupling thereto. In one possible embodiment to reduce capacitive charge build up is to utilize a non-conductive motor casing.
In some embodiments, during charging, it is preferable to lock the rotor to keep the vehicle from inadvertently moving. As there is not always a clutch in electric vehicles, a rotor locking mechanism (not shown) may be used to lock the rotor. In other embodiments, the rotor could be withdrawn from the stator, or in other embodiments, open connections of squirrel cage, for example opening circuiting the shorting rings. In yet another embodiment, a shield may be inserted to block the coupling from the windings to the rotor, for example a conductor sleeve inserted between the rotor and stator when charging.
With charging through the winding of a single phase motor there is not generally a net torque on rotor, but rather it will oscillate back and forth. This is not true for three phase motors, as charging current through winding will create a unidirectional torque on the rotor.
Although not every feature is shown in every embodiment, features from various embodiments may be utilized in other embodiments, for example controllers, capacitor filters, drivers, sensors, etc. Additionally, not every feature shown is necessary in every embodiment, whether explicitly identified as optional or not.
It is worthy to note that any reference to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in an embodiment, if desired. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.
The illustrations and examples provided herein are for explanatory purposes and are not intended to limit the scope of the appended claims. This disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the spirit and scope of the invention and/or claims of the embodiment illustrated.
Those skilled in the art will make modifications to the invention for particular applications of the invention.
The discussion included in this patent is intended to serve as a basic description. The reader should be aware that the specific discussion may not explicitly describe all embodiments possible and alternatives are implicit. Also, this discussion may not fully explain the generic nature of the invention and may not explicitly show how each feature or element can actually be representative or equivalent elements. Again, these are implicitly included in this disclosure. Where the invention is described in device-oriented terminology, each element of the device implicitly performs a function. It should also be understood that a variety of changes may be made without departing from the essence of the invention. Such changes are also implicitly included in the description. These changes still fall within the scope of this invention.
Further, each of the various elements of the invention and claims may also be achieved in a variety of manners. This disclosure should be understood to encompass each such variation, be it a variation of any apparatus embodiment, a method embodiment, or even merely a variation of any element of these. Particularly, it should be understood that as the disclosure relates to elements of the invention, the words for each element may be expressed by equivalent apparatus terms even if only the function or result is the same. Such equivalent, broader, or even more generic terms should be considered to be encompassed in the description of each element or action. Such terms can be substituted where desired to make explicit the implicitly broad coverage to which this invention is entitled. It should be understood that all actions may be expressed as a means for taking that action or as an element which causes that action. Similarly, each physical element disclosed should be understood to encompass a disclosure of the action which that physical element facilitates. Such changes and alternative terms are to be understood to be explicitly included in the description.
Having described this invention in connection with a number of embodiments, modification will now certainly suggest itself to those skilled in the art. The example embodiments herein are not intended to be limiting, various configurations and combinations of features are possible. As such, the invention is not limited to the disclosed embodiments, except as required by the appended claims.
Claims
1. An integrated power conversion system for a vehicle, the integrated power conversion system comprising:
- a) a rotor;
- b) a stator comprising a delta H-bridge connected windings comprising: i) an inverter comprising a first set of pairs of switches connected across a battery bus, a first end of each winding being connected between a respective pair of switches; and ii) a second set of pairs of switches connected across the battery bus in parallel with the first set of switches, a second end of each winding being connected between a respective pair of switches; and
- c) an A/C power port connected to the second end of each winding.
2. The system of claim 1 further comprising interphase transformers connected between the windings and the inverter.
3. The system of claim 1 further comprising a DC power port connected to the battery bus.
4. An integrated motor and battery charging system, the integrated motor and battery charging system comprising:
- a) a rotor;
- b) a stator comprising a delta H-bridge connected windings comprising: i) an inverter; ii) a switching means connected across the battery bus in parallel with the inverter; and iii) the windings being connected between the inverter and the switching means; and
- c) an A/C power port connected to the windings such that when the switching means is open circuited the A/C power port is connected to the battery bus via the windings and the inverter.
5. The system of claim 4 further comprising interphase transformers connected between the windings and the inverter.
6. The system of claim 4 further comprising a DC power port connected to the battery bus.
7. The system of claim 4 wherein each winding is connected between pole switches of the inverter and pole switches of the switching means.
Type: Application
Filed: Mar 30, 2015
Publication Date: Oct 1, 2015
Applicant: AeroVironment, Inc. (Monrovia, CA)
Inventors: Wally Ewald Rippel (Altadena, CA), Scott Garret Berman (Los Angeles, CA)
Application Number: 14/673,863