CN216056358U - Battery equalization system - Google Patents

Battery equalization system Download PDF

Info

Publication number
CN216056358U
CN216056358U CN202120559858.7U CN202120559858U CN216056358U CN 216056358 U CN216056358 U CN 216056358U CN 202120559858 U CN202120559858 U CN 202120559858U CN 216056358 U CN216056358 U CN 216056358U
Authority
CN
China
Prior art keywords
battery
control module
battery pack
circuit
equalization system
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202120559858.7U
Other languages
Chinese (zh)
Inventor
马有镇
江开东
孙丰涛
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Yinlong New Energy Co Ltd
Zhuhai Yinlong Electrical Appliance Co Ltd
Original Assignee
Yinlong New Energy Co Ltd
Zhuhai Yinlong Electrical Appliance Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Yinlong New Energy Co Ltd, Zhuhai Yinlong Electrical Appliance Co Ltd filed Critical Yinlong New Energy Co Ltd
Priority to CN202120559858.7U priority Critical patent/CN216056358U/en
Application granted granted Critical
Publication of CN216056358U publication Critical patent/CN216056358U/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Landscapes

  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

The utility model discloses a battery equalization system. Wherein, this system includes: at least one battery pack, wherein the battery pack comprises a plurality of battery cells; one end of the bidirectional conversion circuit is connected with the battery pack, and the other end of the bidirectional conversion circuit is connected with the battery monomer; the auxiliary power supply circuit is connected with the battery pack; the slave control module is connected with the battery pack and used for sending the acquired state information of the battery pack to the master control module; and the master control module is connected with the slave control module and used for generating a control instruction according to the state information received from the slave control module and sending the control instruction to at least one battery pack. The utility model solves the technical problems that in the related art, the energy of the battery box is balanced by an external storage battery or other energy carriers, the energy of the battery box is balanced by the external energy carriers due to the fact that the wiring harness is required to be connected with other energy carriers outside the battery box, and meanwhile, the wiring harness connection mode is low in safety and poor in reliability.

Description

Battery equalization system
Technical Field
The utility model relates to the field of battery energy storage, in particular to a battery equalization system.
Background
The tradition uses the battery box of initiative equalization technique to realize energy exchange through outside battery or other energy carriers, rely on outside battery or other energy carriers to realize energy exchange promptly and reach the purpose balanced to the battery box energy, nevertheless under this kind of mode, the battery of battery package in the box need be connected with the outer battery of case through the pencil, and the position of placing of battery box is different, the pencil overall arrangement also can be inequality as far as possible, simultaneously, the pencil can cause ageing because of factors such as time, weather, there is the fail safe nature problem in damage etc..
SUMMERY OF THE UTILITY MODEL
The embodiment of the application provides a battery equalization system to at least, solve battery box among the correlation technique and carry out the equilibrium through outside battery or other energy carriers to the battery box energy, and need the pencil to be connected the dependence outside energy carrier that causes with other energy carriers outside the case and carry out the equilibrium to the battery box energy, simultaneously, there is the technical problem that the security is lower, the reliability is relatively poor in the mode that adopts the pencil to connect.
According to an aspect of an embodiment of the present application, there is provided a battery equalization system including: at least one battery pack, wherein the battery pack comprises a plurality of battery cells; one end of the bidirectional conversion circuit is connected with the battery pack, and the other end of the bidirectional conversion circuit is connected with the battery monomer; the auxiliary power supply circuit is connected with the battery pack and is used for supplying power to the bidirectional conversion circuit; the slave control module is connected with the battery pack and used for sending the acquired state information of the battery pack to the master control module; and the master control module is connected with the slave control module and used for generating a control instruction according to the state information received from the slave control module and sending the control instruction to at least one battery pack.
Optionally, an input end of the bidirectional conversion circuit is connected with the battery pack, and an output end of the bidirectional conversion circuit is connected with the battery cell.
Optionally, the bidirectional conversion circuit comprises: the winding selection circuit comprises a first winding circuit and a second winding circuit, wherein the first winding circuit is adopted when the voltage provided by the battery pack is in a first preset range, the second winding circuit is adopted when the voltage provided by the battery pack is in a second preset range, and the maximum value corresponding to the first preset range is smaller than the minimum value corresponding to the second preset range.
Optionally, the bidirectional conversion circuit further comprises: and the pulse width modulation circuit is connected with the first insulated gate field effect transistor so as to control the first insulated gate field effect transistor according to the voltage converted by the pulse width modulation circuit.
Optionally, the first insulated gate field effect transistor includes: the second insulated gate field effect transistor is connected with a primary winding of the winding selection circuit, and the third insulated gate field effect transistor is connected with a secondary winding of the winding selection circuit.
Optionally, the positive electrode and the negative electrode of the auxiliary power supply circuit are respectively connected with the positive electrode and the negative electrode of the battery pack.
Optionally, the auxiliary power supply circuit comprises at least: the power supply conversion isolation circuit is composed of a reverse diode, a fuse, a transient voltage suppression diode, a flyback transformer and a fourth insulated gate field effect transistor, and is used for converting voltage provided by the auxiliary power supply into voltage values with different magnitudes.
Optionally, the slave control module comprises: the control module is connected with the first wireless module and used for collecting state information of the battery pack and sending the state information to the main control module through the first wireless module.
Optionally, the auxiliary power circuit is connected to the slave control module for supplying power to the control module and the first wireless module.
Optionally, the main control module includes: the wireless communication device comprises a second wireless module and a master control module, wherein the second wireless module is connected with the master control module.
In the embodiment of the application, the battery pack is connected with the battery monomer through the bidirectional conversion circuit, and meanwhile, the auxiliary power supply circuit is connected with the battery pack and used for supplying power to the bidirectional conversion circuit; the slave control module is connected with the battery pack and used for sending the acquired state information of the battery pack to the master control module; the main control module is connected with the slave control module and used for generating a control instruction according to the state information received from the slave control module and sending the control instruction to at least one battery pack, so that the problems that in the related art, the energy of the battery box is balanced by an external storage battery or other energy carriers, and the energy of the battery box is balanced by the external energy carriers due to the fact that a wiring harness is connected with other energy carriers outside the battery box are solved, and meanwhile, the technical problems of low safety and poor reliability exist in the wiring harness connection mode.
Drawings
The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the utility model and together with the description serve to explain the utility model without limiting the utility model. In the drawings:
fig. 1 is a schematic structural diagram of a battery equalization system according to an embodiment of the present application;
FIG. 2 is an alternative bi-directional DC-DC-DC conversion circuit according to an embodiment of the present application;
FIG. 3 is an alternative auxiliary power supply circuit according to an embodiment of the present application;
fig. 4 is a schematic diagram of a control structure of a plurality of battery packs according to an embodiment of the present application.
Detailed Description
In order to make the technical solutions of the present invention better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments, not all embodiments, of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the utility model described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Fig. 1 is a schematic structural diagram of a battery equalization system according to an embodiment of the present application, and as shown in fig. 1, the battery equalization system includes: at least one battery pack 10, wherein the battery pack 10 includes a plurality of battery cells 100; a bidirectional conversion circuit 12 having one end connected to the battery pack 10 and the other end connected to the battery cell 100; the auxiliary power supply circuit 14 is connected with the battery pack 10, and the auxiliary power supply circuit 14 is used for supplying power to the bidirectional conversion circuit 12; the slave control module 16 is connected with the battery pack 10 and used for sending the acquired state information of the battery pack 10 to the master control module 18; the main control module 18 is connected with the slave control module 16 and used for generating a control instruction according to the state information received from the slave control module 16 and sending the control instruction to at least one battery pack 10, and the battery balancing system solves the technical problems that in the related art, the battery box balances the energy of the battery box through an external storage battery or other energy carriers, and the energy of the battery box is balanced depending on the external energy carriers due to the fact that a wiring harness is connected with other energy carriers outside the battery box, and meanwhile, the mode of wiring harness connection is low in safety and poor in reliability.
As can be appreciated, sending control instruction execution to the battery pack includes: and sending the control instruction to all the battery cells in the battery pack and/or sending the control instruction to one or more battery cells in the battery pack.
In some optional embodiments of the present application, an input terminal of the bidirectional conversion circuit 12 is connected to the battery pack 10, and an output terminal of the bidirectional conversion circuit 12 is connected to the battery cell 100.
In some embodiments of the present application, the bidirectional conversion circuit 12 includes a winding selection circuit, and it should be noted that the winding selection circuit includes a first winding circuit and a second winding circuit, where the first winding circuit is used when the voltage provided by the battery pack 10 is in a first preset range, and the second winding circuit is used when the voltage provided by the battery pack 10 is in a second preset range, where a maximum value corresponding to the first preset range is smaller than a minimum value corresponding to the second preset range.
In some optional embodiments of the present application, the bidirectional conversion circuit 12 further includes: and the pulse width modulation circuit is connected with the first insulated gate field effect transistor so as to control the first insulated gate field effect transistor according to the voltage converted by the pulse width modulation circuit.
In some embodiments of the present application, the first insulated gate field effect transistor includes: the second insulated gate field effect transistor is connected with a primary winding of the winding selection circuit, and the third insulated gate field effect transistor is connected with a secondary winding of the winding selection circuit. Fig. 2 shows an optional bidirectional DC-DC converter circuit according to the present application, where one end of the bidirectional DC-DC converter is connected to the total positive and total negative of PACK, and the other end is connected to a battery cell requiring equalization, and in order to improve conversion efficiency, the battery end is selected by using a voltage input range, and during equalization charging and discharging, when the total PACK voltage is 9-32V (a first preset range), a half winding (a first winding circuit) is selected, that is, the input end is connected to F3 and disconnected from F1; when the total PACK voltage is 32-55V (second preset range), the full winding (second winding circuit) is selected, i.e., the input terminal is turned on F1 and turned off from F3. The circuit is used for improving the conversion efficiency of the transformer and reducing the energy loss of the transformer.
In some embodiments of the present application, the balancing control of the battery cells according to the control instruction may be implemented by: the single chip microcomputer PWM pin controls U2 and U2 to realize PWM voltage conversion, low-voltage PWM output by the single chip microcomputer is converted into voltage PWM suitable for controlling an NMOS (N-channel metal oxide semiconductor), and as shown in figure 2, the voltage 12V _ MCU is converted to respectively control a first insulated field effect transistor Q2 and a second insulated field effect transistor Q3. The control Q2 may also be provided with a MOS driver for rail-to-rail output, since it is necessary to isolate the battery cells from the battery pack. When the battery cell is charged in an equalizing manner, the Q3 is turned off, the output voltage is controlled by controlling the duty ratio of the NMOS Q2, it should be noted that the magnitude of the voltage output is adjusted by the charging current, taking 2A as an example, when the equalizing current is greater than 2A, the output voltage is reduced by reducing the duty ratio, and then the equalizing current is reduced; when the equalizing current is less than 2A, the output voltage is increased by increasing the duty ratio, and the equalizing current is increased. When the single body is discharged in an equalizing way, the Q2 is cut off, and the duty ratio of the Q3 is controlled to adjust the equalizing current, the method is the same as the charging method, and the description is omitted.
In some optional embodiments of the present application, the positive electrode and the negative electrode of the auxiliary power circuit 14 are respectively connected to the positive electrode and the negative electrode of the battery pack 10. Note that the auxiliary power supply circuit 14 includes at least: the power supply conversion isolation circuit is composed of a reverse diode, a fuse, a transient voltage suppression diode, a flyback transformer and a fourth insulated gate field effect transistor, and is used for converting voltage provided by the auxiliary power supply into voltage values with different sizes.
As shown in fig. 3, an optional auxiliary power circuit 14 according to the present application is shown, and it is easy to note that the auxiliary power circuit 14 respectively obtains power from a total positive BAT + and a total negative BAT-of a battery PACK, and sends the power to a primary coil of a flyback transformer after passing through a reverse diode, a fuse and a transient voltage suppression diode TVS, and controls an external N communication fet NMOS Q4 through a PWM controller in a low power BICMOS current mode to implement power isolation and conversion, and it can be understood that this IC may be replaced with an IC with an internal MOS, where it is to be noted that +12V _ P supplies power to a battery end element, 12V _ MCU supplies power to a single chip microcomputer through voltage reduction, and 3.3V _ wide supplies power to a WIRELESS module.
In some embodiments of the present application, the slave control module 16 includes: the battery pack comprises a control module and a first wireless module, wherein what needs to be described is that the control module is connected with the first wireless module, and the control module is used for collecting the state information of the battery pack 10 and sending the state information to the main control module 18 through the first wireless module.
In some embodiments of the present application, the auxiliary power circuit 14 is connected to the slave control module 16 for supplying power to the control module and the first wireless module.
It notices easily that all get electric and the energy carrier of conversion all come from the battery package itself in the embodiment of this application, and irrelevant with external power source, so can inside carry out initiative equilibrium by oneself when the battery is placed for a long time, the battery monomer that the high battery monomer of energy supplyes the low battery monomer of energy, realizes the inner loop, fine solution traditional initiative equalization technique to the reliance of outside battery, avoid placing the battery uniformity problem that causes for a long time.
In some optional embodiments of the present application, the main control module 18 includes: the wireless communication device comprises a second wireless module and a master control module, wherein the second wireless module is connected with the master control module.
The application still provides a control structure picture when a plurality of battery package PACK, be the control structure picture of compriseing a plurality of battery package PACK as shown in FIG. 4, wherein, gather balanced module and wireless module and constitute from controlling the module, should be connected with PACK from controlling module one side, the opposite side is connected with host system, and wherein, this host system includes: the device comprises a wireless module and a master control module.
It is easy to note that the above battery equalization system can be applied to a scenario in which there are a plurality of battery packs, since the battery equalization system includes: at least one battery pack 10, wherein the battery pack 10 includes a plurality of battery cells 100; a bidirectional conversion circuit 12 having one end connected to the battery pack 10 and the other end connected to the battery cell 100; the auxiliary power supply circuit 14 is connected with the battery pack 10, and the auxiliary power supply circuit 14 is used for supplying power to the bidirectional conversion circuit 12; the slave control module 16 is connected with the battery pack 10 and used for sending the acquired state information of the battery pack 10 to the master control module 18; the master control module 18 is connected to the slave control module 16, and is configured to generate a control instruction according to the status information received from the slave control module 16, and send the control instruction to the at least one battery pack 10, so that the technical problems that in the related art, the battery box balances the energy of the battery box through an external storage battery or other energy carriers, and the energy of the battery box is balanced depending on the external energy carriers due to the fact that a wire harness is connected to other energy carriers outside the battery box, and meanwhile, the mode of connecting the wire harness is low in safety and poor in reliability are solved.
It can be understood that in this embodiment, all energy carriers of getting electricity and converting all come from the battery package itself, and are irrelevant with external power source, so can inside voluntarily carry out initiative equilibrium when the battery is placed for a long time, the battery monomer that the high battery of energy supplyes the battery monomer that the energy is low, realizes the inner loop, fine solution traditional initiative equalization technique to the reliance of outside battery, avoid placing the battery uniformity problem that causes for a long time.
In some embodiments of the present application, the balancing control of the battery cells according to the control instruction may be implemented as follows: the single chip microcomputer PWM pin controls U2 and U2 to realize PWM voltage conversion, low-voltage PWM output by the single chip microcomputer is converted into voltage PWM suitable for controlling an NMOS (N-channel metal oxide semiconductor), and as shown in figure 2, the voltage 12V _ MCU is converted to respectively control a first insulated field effect transistor Q2 and a second insulated field effect transistor Q3. The control Q2 may also be provided with a MOS driver for rail-to-rail output, since it is necessary to isolate the battery cells from the battery pack. When the battery cell is charged in an equalizing manner, the Q3 is turned off, the output voltage is controlled by controlling the duty ratio of the NMOS Q2, it should be noted that the magnitude of the voltage output is adjusted by the charging current, taking 2A as an example, when the equalizing current is greater than 2A, the output voltage is reduced by reducing the duty ratio, and then the equalizing current is reduced; when the equalizing current is less than 2A, the output voltage is increased by increasing the duty ratio, and the equalizing current is increased. When the single body is discharged in an equalizing way, the Q2 is cut off, and the duty ratio of the Q3 is controlled to adjust the equalizing current, the method is the same as the charging method, and the description is omitted.
The present application further provides a processor for running a program, wherein the program performs the above embodiments when running.
It should be noted that, reference may be made to the relevant description of fig. 1 to fig. 4 for a preferred implementation of the above-described embodiment, and details are not described here again.
The above-mentioned serial numbers of the embodiments of the present application are merely for description and do not represent the merits of the embodiments.
In the above embodiments of the present invention, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
In the embodiments provided in the present application, it should be understood that the disclosed technology can be implemented in other ways. The above-described embodiments of the apparatus are merely illustrative, and for example, a division of a unit may be a division of a logic function, and an actual implementation may have another division, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted, or may not be executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, units or modules, and may be in an electrical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be provided in one place, or may be distributed over a plurality of units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that it is obvious to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and these modifications and improvements should also be considered as the protection scope of the present invention.

Claims (10)

1. A battery equalization system, comprising:
at least one battery pack, wherein the battery pack includes a plurality of battery cells;
one end of the bidirectional conversion circuit is connected with the battery pack, and the other end of the bidirectional conversion circuit is connected with the single battery;
the auxiliary power supply circuit is connected with the battery pack and is used for supplying power to the bidirectional conversion circuit;
the slave control module is connected with the battery pack and used for sending the acquired state information of the battery pack to the master control module;
the master control module is connected with the slave control module and used for generating a control instruction according to the state information received from the slave control module and sending the control instruction to the at least one battery pack.
2. The battery equalization system of claim 1, wherein an input of the bidirectional conversion circuit is connected to the battery pack, and an output of the bidirectional conversion circuit is connected to the battery cell.
3. The battery equalization system of claim 1, wherein the bidirectional translation circuit comprises: the winding selection circuit comprises a first winding circuit and a second winding circuit, wherein the first winding circuit is adopted when the voltage provided by the battery pack is in a first preset range, the second winding circuit is adopted when the voltage provided by the battery pack is in a second preset range, and the maximum value corresponding to the first preset range is smaller than the minimum value corresponding to the second preset range.
4. The battery equalization system of claim 3, wherein said bidirectional translation circuit further comprises: and the pulse width modulation circuit is connected with the first insulated gate field effect transistor so as to control the first insulated gate field effect transistor according to the voltage converted by the pulse width modulation circuit.
5. The battery equalization system of claim 4, wherein the first insulated gate field effect transistor comprises: the second insulated gate field effect transistor is connected with a primary winding of the winding selection circuit, and the third insulated gate field effect transistor is connected with a secondary winding of the winding selection circuit.
6. The battery equalization system of claim 1, wherein the positive and negative poles of the auxiliary power circuit are connected to the positive and negative poles of the battery pack, respectively.
7. The battery equalization system of claim 6, wherein the auxiliary power circuit comprises at least: the power supply isolation conversion circuit is composed of a reverse diode, a fuse, a transient voltage suppression diode, a flyback transformer and a fourth insulated gate field effect transistor, and is used for converting the voltage provided by the auxiliary power supply into different voltage values.
8. The battery equalization system of claim 1, wherein the slave control module comprises: the control module is connected with the first wireless module and used for acquiring the state information of the battery pack and sending the state information to the main control module through the first wireless module.
9. The battery equalization system of claim 8, wherein the auxiliary power circuit is coupled to the slave control module for powering the control module and the first wireless module.
10. The battery equalization system of claim 1, wherein the master control module comprises: the wireless communication device comprises a second wireless module and a master control module, wherein the second wireless module is connected with the master control module.
CN202120559858.7U 2021-03-18 2021-03-18 Battery equalization system Active CN216056358U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202120559858.7U CN216056358U (en) 2021-03-18 2021-03-18 Battery equalization system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202120559858.7U CN216056358U (en) 2021-03-18 2021-03-18 Battery equalization system

Publications (1)

Publication Number Publication Date
CN216056358U true CN216056358U (en) 2022-03-15

Family

ID=80596066

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202120559858.7U Active CN216056358U (en) 2021-03-18 2021-03-18 Battery equalization system

Country Status (1)

Country Link
CN (1) CN216056358U (en)

Similar Documents

Publication Publication Date Title
US10917023B2 (en) Power conversion system and method for pre charging DC-Bus capacitors therein
JP5333946B2 (en) Energy storage system
CN103168406B (en) Battery pack, for the method for batteries charging/electric discharge and power consumption devices
US11791721B2 (en) Multi-mode DC-to-DC power converter
US20210126541A1 (en) Power conversion system
EP3783784A2 (en) Balancing multilevel dc-dc converter apparatus
US10615612B2 (en) Battery apparatus and cell balancing circuits
US9425717B2 (en) Device and method for supplying an electric drive with electric current
CN112769181A (en) Bidirectional charging circuit and device of electric power storage equipment and control method
US20220069610A1 (en) Step-down circuit, electronic device, and step-down method
CN104953692A (en) Power supply system
CN101304180B (en) Composition energy-saving non power brake system and bidirectional transducer module as well as power transferring method
US11780342B2 (en) On-board charging and discharging apparatus, charging and discharging system thereof, and electric vehicle
CN216056358U (en) Battery equalization system
Pham et al. A low cost, small ripple, and fast balancing circuit for Lithium-Ion battery strings
CN101917042A (en) Lithium battery charger and DC booster integrated circuit system
CN103795116A (en) Power supply change-over and control device, and power supply method and system
CN116526531A (en) Energy storage device and control method thereof
CN110892603A (en) Battery control circuit, battery and unmanned aerial vehicle
CN117411155A (en) Charging device, charging pile and charging system
Ilango et al. A hybrid photovoltaic-battery powered DC-DC converter with high conversion ratio and reduced switch stress
WO2011140841A1 (en) Conjugate multi-directional inversion power supply
Ramaprabha et al. An active battery equalizer for series connected battery applications
Song et al. Design considerations for energy storage power electronics interfaces for high penetration of renewable energy sources
CN106100066B (en) A kind of miniature charging station of thin film solar

Legal Events

Date Code Title Description
GR01 Patent grant
GR01 Patent grant