This application relates to a battery pack system and a method for transferring power to and/or from the battery pack. In one implementation, the system is configured to include an adaptor for transferring power to and/or from a device coupled to the battery pack through the adaptor.
Removable, rechargeable, secondary battery packs are becoming ubiquitous as more and more devices become wireless to take advantage of the advances in battery technology.
Such battery packs are commonly part of cordless power tool systems and are designed and configured to operate with a variety of cordless power tool, such as drills, circular saws and grinders, for example. The battery packs and the power tools include an interface system that enables the battery pack to couple to the power tool, as is well known in the art. Typically, these battery packs are charged using battery pack chargers that are designed and configured to charge specific battery packs. These chargers are designed and configured to plug into a wall outlet for access to alternating current (AC) mains line (utility) power or some other source of AC power, such as a generator. The ability to use the aforementioned battery packs to power unrelated devices, such as mobile phones or low power lights is also desirable.
There are adaptors that may be coupled to the rechargeable battery packs that enable the battery pack to provide power to such unrelated devices.
The power transfer adaptor is both a tool and a charger designed to take advantage of USB 3.1's new PD (Power Delivery) specification. The feature includes the ability to supply bidirectional power up to 100 W. Because the adaptor is bidirectional, it will have many of the same properties of both a tool and a charger. For example, as a charger the adaptor can accept power up to 100 W from Type C source devices, incorporating legacy charger interfaces, standards & best practices. And for example, as a tool the adaptor can discharge a rechargeable battery pack to charge and power various devices through its Type C Port up to 100 W and through its Type A Port up to 12 W.
The adaptor leverages the Power Delivery (PD) or USB PD standard. The PD standard that allows devices to send or receive power through its Type C port (bidirectional power flow) up to 100 W and at varying voltage and current profiles. These products allow for discrete voltages of 5, 9, 12, 15, and 20V and currents up to 5 A. The PD standard uses a PD contract to establish a relationship between the PD device (the adaptor in this case) and a connected device. The contract is an agreement between two PD devices connected via Type C Cable. There are many nuances but the most basic constraints for each device are: (1) the source must establish and maintain the agreed upon voltage within +/−4% while sourcing all the way up to the agreed upon maximum current and (2) the sink may pull any amount of current from 0 A all the way up to the maximum agreed upon current. The current may not exceed the maximum for more than a few milliseconds.
A PD charger/provider/source is the device in the PD contract that agrees to send power to its partner device. A PD consumer/load/sink is the device in the PD Contract that agrees to accept power from its partner device. A PD dual role port (DRP) device is a device that is capable of being either a source or a sink depending on what is connecting to and its internal state. The adaptor is a DRP device.
The adaptor can provide cordless USB “C” power delivery limited only by the available battery packs, can choose a longer run time or shorter run time battery pack to customize a user experience, and can choose a larger or a smaller battery pack size based on ergonomic preferences.
These and other advantages and features will be apparent from the description and the drawings.
The upper housing 14 and the lower housing 16 form a cavity when coupled together. The adaptor 10 may include a variety of electrical and electronic components in the cavity. For example, the adaptor 10 may include a printed circuit board (PCB) 20 including a plurality of components 22, such as resistors, capacitors, connectors, integrated circuits, etc., mounted to the PCB 20. The adaptor 10 may also include a terminal block 24 in the cavity. The terminal block 24 may include a housing 26 and a plurality of adaptor terminals 28 fixedly positioned in the housing 26. The adaptor 10 may also include a plurality of wires 30 coupling one or more of the plurality of terminals 26 to the PCB 20. The adaptor 10 may also include a belt clip 31 coupled to the upper housing 14. The upper housing 14 may also include a plurality of connector openings 32a, 32b for providing access to connectors (ports) 34a, 34b coupled to the PCB 20. The adaptor may include a USB Type C port 34a and a USB Type A port 34b. In an alternate embodiment, the adaptor 10 may include a second USB Type C port instead of the USB Type A port. In another alternate embodiment, the adaptor 10 may include ports—either USB Type A, USB Type B or USB Type C—in addition to the two ports illustrated.
Generally, the adaptor 10 operates with a removable battery pack. This enables the adaptor 10 to provide power to a variety of products and devices from a variety of battery packs. The adaptor 10 is able to provide bi-directional power transfer with the detachable battery pack. The adaptor may include terminals 28 to voltage tap the plurality of battery cells in the detachable battery pack and provide access to the voltage tap values. The adaptor 10 includes an automatic sleep mode in response to an undervoltage condition, an idle condition, a no cable attached condition and for various fault conditions. The adaptor 10 may also include a wake-up feature for a cable insertion condition. The adaptor 10 includes a peak current control monitor circuit to ensure that the current into or out of the adaptor 10 does not exceed pre-established values.
The adaptor 10 includes interface features similar to the power tool 110 to enable the adaptor 10 to couple to the battery pack 100. For example, the adaptor 10 includes a set of rails 36 and a set of grooves 38 and a latch recess 40. The system may also include a bi-directional USB Type C cord 42 include a USB Type C male connector 44a, 44b at each end of the cord 42. The system may also include a plug-in power supply or rectifier 46 including a USB Type C port 48. In this system, one male connector 44a of the cord 42 plugs into the USB Type C port 34a of the adaptor 10 and one male connector 44b of the cord 42 plugs into the USB Type C port 48 of the power supply 46. The power supply 46 plugs into an outlet coupled to an AC power source, for example, a utility mains line or a portable generator. In this manner, the adaptor 10 is able to provide a charge to the battery pack 100 from the outlet.
Alternatively, the adaptor 10 may be coupled to a DC power source. Specifically, the male connector 44b of the USB Type C cord 42 may be coupled to a USB Type C port 50 in an automobile 52 to source power from a battery or alternator in the automobile 52.
The adaptor 600 includes a plurality of terminals TT1-TT8 (sometimes referred to as a set of terminals). The set of adaptor terminals includes a first subset of adaptor terminals TT1 (negative power terminal) and TT2 (positive power termina) that serve as power terminals for transferring power to charge or discharge the battery cells of a battery pack coupled to the adaptor 600. The set of adaptor terminals may also include a second subset of adaptor terminals TT3-TT8. The second subset of adaptor terminals TT3-TT8 serve as signal or data terminals for transferring low current, signals to indicate various pieces of data regarding an attached battery pack 500. The adaptor 600 may include a first USB type C port. The adaptor 600 may include a first USB type A port. In alternate embodiments, the adaptor 600 may include a second USB type C port instead of the USB type A port. The USB type C port may include a first positive node, a second positive node, a negative node and data node. These nodes may be formed as terminals or pins on the port. The adaptor 600 may include an ideal diode coupled to the first positive node of the type C port. The adaptor 600 may include a controllable switch coupled to the second positive node of the type C port. The first positive node and the second positive node of the type C port are coupled to the positive power terminal TT2 and the negative node of the type C port is coupled to the negative power terminal TT1.
The adaptor 600 may include a first control module (sometimes also referred to as a control circuit or a controller or a microcontroller or control circuitry) and a second control module (sometimes also referred to as a control circuit or a controller or a microcontroller or control circuitry). The adaptor 600 may include a bi-directional non-inverting buck/boost converter coupled between the positive power terminal TT2 and the first and the second positive nodes of the type C port. The buck/boost converter may be coupled to the first control module. The adaptor may include battery disconnect switch coupled between the buck/boost converter and the positive power terminal TT2. The USB type A port may include a positive node, a negative node and data node. These nodes may be formed as terminals or pins on the port. The adaptor 600 may include an ideal diode coupled to the first positive node of the type A port. The adaptor 600 may include a buck converter coupled between the positive power terminal TT2 and the positive node of the type A port. The buck converter may be coupled to the second control module. The adaptor may include a OVP module coupled to the adaptor power terminals TT1, TT2 and to the adaptor signal terminals TT5-TT8. The OVP module may be coupled to the second control module. The adaptor 600 may include a first thermistor circuit and a second thermistor circuit to monitor the temperature of the adaptor 600 and its components. The first and second thermistor circuits may be coupled to the second control module.
The first control module may be coupled to the battery disconnect switch to control the battery disconnect switch based on various signals received by the first control module. The first control module may be connected to the TT4 signal terminal. The second control module may be connected to the TT3 signal terminal. The second control module may be coupled to the control switch coupled to the second positive node of the type C port. The second control module may control the control switch coupled to the second positive node of the type C port based upon one or more signals received by the second control module.
After a user inserts a source into the adaptor Type C port, the adaptor performs a negotiation with the partner device. When negotiation is complete, a PD contract is established wherein the partner device Type C source is obligated to provide the contract voltage and our unit is obligated to not exceed the agreed upon maximum current level. Typical voltage and current levels are as follows:
The adaptor can read the PD contract information and adapt its current intake accordingly.
Current Level Selection
When selecting a current level for charging, the adaptor will consider and comply with: the partner device (charger's) maximum current output level (Ibus limit) and the battery's maximum safe allowable current level (Ibat limit). The adaptor's software is perpetually monitoring both the PD/Type C activity to determine the Ibus limit and battery/ambient conditions to determine the Ibat limit.
Partner Device & Ibus Limit
As mentioned above, the adaptor will attempt to pull current commensurate with the maximum current the partner device can supply minus about 5%. This ensures we minimize charge time but do not exceed the PD contract conditions.
Pack ID Limits
The adaptor reads and considers both the ID Resistor (ID line to ground) and the ID Capacitor (NTC line to ground) of the battery pack with independent microcontrollers and chooses the lower of the two values to select the maximum amount of current the battery pack can take when charging the battery pack.
Charger NTC & Thermal Foldback
In order to prevent the adaptor from overheating, there is a thermal foldback routine. To do this we read the two on-board NTCs and adjust the battery current accordingly. The routine is as follows: at 115° C. we reduce the maximum allowable battery current from 4 A or higher to 2 A maximum, at 95° C. we re-allow the maximum current to be 4 A or higher (pack dependent), at 125° C. we disallow current flow entirely, at 120° C. we re-allow current flow of 2 A.
Pack NTC Limitations
In order to protect the attached battery and comply with charging schemes for the attached battery pack, the adaptor must react to the pack NTC conditions as follows: below 0° C., allow 0 A charging, between 0° C. and 10° C., allow 2 A maximum charging, above 60° C. allow 0 A charging; each options including a few degrees of hysteresis.
Over-Voltage Protection Reset Limits & Topping Off
The adaptor uses top-off “step down” charging schemes similar to charger. The rule base is as follows: for bulk charge (0 OVP trips) pull the maximum amount of current allowed by all the other rules (CNTC, Pack, Ibus, Pack ID); after 1 OVP Reset: set the limit to 2 A; after 2 OVP Resets: set the limit to 1 A. For all subsequent resets, set the limit to 300 mA as a maintenance charge. However, if a Type A device is attached, the minimum current will be 2 A instead of 300 mA in order to ensure that adaptor charges the attached battery pack at a rate that is faster than the Type A discharge rate.
Type C Sourcing/Discharging
After a user inserts a sink into the adaptor Type C port, the adaptor performs a contract negotiation with the partner device. When the contract negotiation is complete, a PD contract is established wherein the partner device Type C sink is obligated to pull less than the PD contract maximum current and the adaptor is obligated to provide the requested voltage within +/−5%. If the battery pack NTC reading indicates a reading greater than 70° C. the adaptor will not allow discharge through the Type C port. If one of the adaptor NTCs detects a temperature greater than 120° C. the adaptor will not allow discharge through the Type C port. If the adaptor detects a stack voltage of <15 V it will cease to allow discharge on the Type C port. The adaptor will only re-enable discharge once the stack voltage exceeds 17.8 V.
Type A Sourcing/Discharging
After a user inserts a Type A device into the Type A port of the adaptor, the adaptor detects the presence of a load and turns on the Type A bus within ˜1 s. If the adaptor temperature or the battery pack temperature falls below −20° C. the adaptor will stop current flow through the Type A port. If the adaptor detects a stack voltage of <15 V it will stop discharge on the Type A port. The adaptor will only re-enable discharge once the stack voltage exceeds 15.5 V. The Type A bus will remain on for at least 8 hours. At that point the adaptor checks whether a device is still inserted. If a device is still inserted to the Type A port, the adaptor keeps the bus on. If a device is not still inserted to the Type A port, then the adaptor turns off the Type A port.
Numerous modifications may be made to the exemplary implementations described above. These and other implementations are within the scope of this application.
This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63/013,909, filed Apr. 22, 2020, titled “Battery Pack Power Transfer Adaptor.”
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