POWER EQUIPMENT WITH HYBRID POWER SUPPLY

A hybrid power supply for power equipment or a power tool is disclosed. The hybrid power supply is advantageously configured to operate in several different operating modes depending on the performance or power requirement of the equipment or tool, as well as depending on whether AC power is available. Particularly, the hybrid power supply enables the equipment or tool to operate using battery power, battery power, or both. Additionally, the hybrid power supply enables charging of attached batteries and enables providing power to an AC accessory connected to the equipment or tool.

FIELD

The device and method disclosed in this document relates to power supplies and, more particularly, to a hybrid power supply for power equipment.

BACKGROUND

Unless otherwise indicated herein, the materials described in this section are not admitted to be the prior art by inclusion in this section.

Conventional power tools and other power equipment incorporate a variety of power sources depending on their specific requirements. For example, some equipment is battery-powered (i.e., cordless) and receives power via a battery, which is generally rechargeable or replaceable. Battery-powered equipment provides greater mobility and flexibility, but runtime and maximum power output is limited by the capacity and output of the battery. For equipment that requires less mobility, it is common to receive power via a cord connected to a standard electrical outlet or other alternating-current (AC) power source. Corded equipment can thus be provided with continuous power, so long as it is sufficiently near the AC power source. However, even corded equipment has a maximum power output that may be enforced by a circuit breaker.

Common alternatives to battery-powered equipment, where higher power and mobility are required include gasoline-powered equipment that incorporates a small gasoline engine. Gasoline-powered equipment provide higher power, while maintaining some level of mobility. Common alternatives to stationary corded equipment where very high power is required include pneumatic and hydraulic equipment. Such equipment is useful in heavy duty and industrial applications. However, gasoline, pneumatic, and hydraulic equipment are often more challenging to operate and more expensive to maintain compared to electric equipment, particular for typical consumers and hobbyists.

What is needed is a power supply that provides the ease of use and maintenance of electric equipment, while flexibly providing mobility when it is need and very high power when it is needed.

SUMMARY

A power supply for a device is disclosed. The power supply comprises a first direct-current (DC) bus having a first DC voltage. The device is configured to receive power from the first DC bus. The power supply further comprises first power electronics configured to provide power from an alternating-current (AC) power source to the first DC bus. The power supply further comprises a second DC bus having a second DC voltage. The second DC voltage is less than the first DC voltage. The power supply further comprises second power electronics configured to provide power from the second DC bus to the first DC bus. The power supply further comprises third power electronics configured to provide power from at least one battery pack to the second DC bus. The power supply further comprises a controller. The controller is configured to, in a first operating mode, operate the first power electronics to provide power from the AC power source to the first DC bus. At least one load of the device is provided with power from the first DC bus in the first operating mode. The controller is further configured to, in a second operating mode, operate the second power electronics and the third power electronics to provide power from the at least one battery pack to the first DC bus. At least one load of the device is provided with power from the first DC bus in the second operating mode.

A further power supply for a device is disclosed. The power supply comprises a direct-current (DC) bus having a first DC voltage. The device is configured to receive power from the DC bus. The power supply further comprises first power electronics configured to provide power from an alternating-current (AC) power source to the DC bus. The power supply comprises second power electronics configured to provide power from at least one battery pack to the DC bus. The power supply comprises a controller. The controller is configured to, in a first operating mode, operate the first power electronics to provide power from the AC power source to the DC bus. At least one load of the device is provided with power from the DC bus in the first operating mode. The controller is further configured to, in a second operating mode, operate the second power electronics to provide power from the at least one battery pack to the DC bus, at least one load of the device being provided with power from the DC bus in the second operating mode.

A power tool is disclosed. The power tool comprises an electric motor configured to drive a tool. The power tool further comprises a direct-current (DC) bus having a DC voltage. The electric motor is operably connected to receive power from the DC bus. The power tool further comprises first power electronics configured to provide power from an alternating-current (AC) power source to the DC bus. The power tool further comprises second power electronics configured to provide power from at least one battery pack to the second DC bus. The power tool further comprises a controller. The controller is configured to, in a first operating mode, operate the first power electronics to provide power from the AC power source to the DC bus. The electric motor is provided with power from the DC bus in the first operating mode. The controller is further configured to, in a second operating mode, operate the second power electronics to provide power from the at least one battery pack to the DC bus. The electric motor is provided with power from the DC bus in the second operating mode.

DETAILED DESCRIPTION

Overview

FIG.1is a schematic drawing showing a piece of power equipment10having a hybrid power supply20. In some embodiments, the power equipment10may, for example, comprise a tabletop power tool such as a table saw, a band saw, a miter saw, a scroll saw, a drill press, a router table, a bench grinder, or a thickness planer. Likewise, the power equipment10may also include equivalent and related handheld power tools. In other embodiments, the power equipment10may, for example, comprise an outdoor power equipment, such as a lawnmower, a leaf blower, a snow blower, a chainsaw, or a pressure washer. In at least some embodiments, the hybrid power supply20is directly integrated with the power equipment10, but may also be provided separately and discretely in some embodiments.

The hybrid power supply20is advantageously configured to operate in several different operating modes depending on the performance or power requirement of the power equipment, as well as depending on whether AC power is available. To this end, the power equipment10and/or the hybrid power supply20includes one or more controllers for operating power electronics of the hybrid power supply20. In one embodiment, a power controller30is provided as a master controller and is configured to select which operating mode(s) the hybrid power supply20is to be operated in and operate the power electronics thereof according to the selected operating mode. It will be recognized by those of ordinary skill in the art that a “controller” includes any hardware system, hardware mechanism or hardware component that processes data, signals, or other information. Thus, the power controller30may include a system with a central processing unit, multiple processing units, dedicated circuitry for achieving specific functionality, or other systems.

In some embodiments, the power equipment10further includes a physical user interface, such as one or more buttons or switches, via which a user can manually set an operating mode of the hybrid power supply20.

In a first operating mode of the hybrid power supply20, the power equipment10is provided with power from an alternating-current (AC) power source50that is connected to the power equipment10, e.g., via a power cord. In at least some embodiments, the AC power source50is a standard electrical outlet providing AC voltages between 110V˜230V at a frequency between 50-60 Hz. However, the AC power source50may comprise any external system that the power equipment10can connect with to receive AC power, such as a gasoline generator or another alternative power source. It should be appreciated that the first operating mode has the advantage of providing continuous and relatively high power. In some embodiments, the power controller30is configured to automatically switch the hybrid power supply20to the first operating mode in response to the power equipment10being activated while the hybrid power supply20is connected to the AC power source50.

In a second operating mode of the hybrid power supply20, the power equipment10is provided with power from at least one battery pack40A,40B,40C. In at least some embodiments, each battery pack40A-C is a rechargeable and discretely enclosed battery pack that is configured to connect with the battery connection interface. In at least some embodiments, each battery pack40A-C is removably connected to the power equipment10via a battery connection interface (not shown). Each battery pack40A-C is configured to provide a direct-current (DC) voltage, e.g., 18V or 36V. In some embodiments, the hybrid power supply20and the battery connection interface are configured to receive and operate with battery packs providing multiple different voltages and/or form factors. It should be appreciated that the second operating mode has the advantage of greater mobility and flexibility, but has a limited runtime and power output, compared to the first operating mode in which a nearby AC power source is required. In some embodiments, the power controller30is configured to automatically switch the hybrid power supply20to the second operating mode in response to the power equipment10being activated while the hybrid power supply20is disconnected from the AC power source50. In at least some embodiments, in the second operating mode, the current draw from each battery pack40A-C is optimized based on the load, the battery capacity, the battery temperature, etc., to maximize efficiency and thermal performance.

In a third operating mode of the hybrid power supply20, the battery pack(s)40A-C are provided with power from the AC power source50that is connected to the power equipment10and the battery pack(s)40A-C are charged. It should be appreciated that the third operating mode can be usefully leveraged to recharge the battery pack(s)40A-C when the power equipment10is connected to the AC power source50, but is not currently being used itself. In some embodiments, the power controller30is configured to automatically switch the hybrid power supply20to the third operating mode in response to the power equipment10being deactivated (or otherwise not being used) while the hybrid power supply20being connected to the AC power source50. In some embodiments, the power controller30is configured to cause the battery pack(s)40A-C to be charged simultaneously, sequentially, or a combination of both, depending on how many batteries are connected to the system, a state of charge of each battery, or a load current limit or a load power limit associated with the AC power source50, etc.

In a fourth operating mode of the hybrid power supply20, an AC accessory60that is removably connected to the power equipment10is provided with AC power from the hybrid power supply20, e.g., from the battery pack(s)40A-C and/or the AC power source50. The AC accessory60may be any device that is configured to receive and operate using AC power. In some embodiments, the AC accessory60may, for example, be a handheld power tool, such as a drill, a saw, a router, or a sander. In some embodiments, the AC accessory60is connected to the power equipment10and/or the hybrid power supply20via a standard electrical outlet (not shown) that is arranged on a housing of the power equipment10. It should be appreciated that the fourth operating mode has the advantage of providing AC power to smaller accessory devices from the power equipment10when an AC power source is not nearby or when a sufficient number of electrical outlets is not available. In some embodiments, the power controller30is configured to automatically switch the hybrid power supply20to the fourth operating mode in response to the hybrid power supply20being connected to the AC accessory60.

In a fifth operating mode of the hybrid power supply20, the power equipment10is provided with power both from the AC power source50and from the battery pack(s)40A-C, simultaneously. In this way, the power equipment10can be operated with the combined power output of the AC power source50and the battery pack(s)40A-C. It should be appreciated that the fifth operating mode is advantageous when the power or performance requirement of the power equipment10would otherwise exceed the load limitations of the AC power source50alone, e.g., the load would trip a circuit breaker or blow a fuse. In some embodiments, the power controller30is configured to automatically switch the hybrid power supply20to the fifth operating mode in response to the hybrid power supply20being connected to the AC power source50and a power requirement (e.g., a load current or load power) of the power equipment10exceeding a predetermined threshold, e.g., a load current limit or a load power limit associated with the AC power source50.

It should be appreciated that the operating modes of the hybrid power supply20that are described herein are not necessarily mutually exclusive of one another. In some cases, the hybrid power supply20is configured to operate in more than on operating mode at the same time. For example, in one embodiment, the hybrid power supply20is configured such that it can be operating the first operating mode or the second operating mode to provide power to operate the power equipment10, while simultaneously operating in the fourth operating mode to provide power to the AC accessory60.

Hybrid Power Supply

FIG.2is a schematic drawing that illustrates an architecture of the hybrid power supply20. The hybrid power supply20comprises a variety of power electronics configured to achieve the functionalities described herein. Such power electronics may include arrangements of circuit components such as relays, contactors, diodes, solid-state switches, resistors, capacitors, and inductors, which are not described in detail herein.

The hybrid power supply20has a high voltage DC bus110configured to distribute power to high voltage loads in the power equipment10. As will be appreciated from the descriptions below, the high voltage DC bus110can receive power either from the AC power source50or from the battery pack(s)40A-C. In some embodiments, the high voltage DC bus110has a nominal voltage of 400 Volts.

In the illustrated embodiment, the high voltage loads include a high voltage brushless DC motor120of the power equipment10. In at least some embodiments, the high voltage brushless DC motor120is configured to drive a tool, such as a drill bit, saw blade, or the like. The high voltage brushless DC motor120is operated by a high voltage motor drive130having power electronics configured to receive power from the high voltage DC bus110and apply suitable driving currents to high voltage brushless DC motor120. It should be appreciated that the power equipment10may include a variety of other high voltage loads.

The hybrid power supply20further includes power electronics, in particular an AC/DC converter, configured to provide power from the AC power source50to the high voltage DC bus110. In at least some embodiments, this AC/DC converter is configured to be operated as a bidirectional AC/DC converter140. In a converter or rectifier mode of operation, the bidirectional AC/DC converter140is configured to provide power from the AC power source50to the high voltage DC bus110by converting an AC voltage of the AC power source50into the nominal voltage of the high voltage DC bus110. In an inverter mode of operation, the bidirectional AC/DC converter140is configured to provide power from the high voltage DC bus110to the AC accessory60connected to the hybrid power supply20by converting the nominal voltage of the high voltage DC bus110from the high voltage DC bus110into an AC voltage for the AC accessory60. In at least one embodiment, the bidirectional AC/DC converter140has a totem-pole power factor correction (PFC) topology.

The hybrid power supply20further includes a low voltage DC bus150. As will be appreciated from the descriptions below, the low voltage DC bus150is an intermediate bus between the high voltage DC bus110and the battery pack(s)40A-C. In some embodiments, the low voltage DC bus150has a nominal voltage that is less than the nominal voltage of the high voltage DC bus110.

The hybrid power supply20further includes power electronics, in particular a DC/DC converter, configured to provide power from the low voltage DC bus150to the high voltage DC bus110. In at least some embodiments, this DC/DC converter is a bidirectional DC/DC converter160. In a step-up mode of operation, the bidirectional DC/DC converter160is configured to provide power from the low voltage DC bus150to the high voltage DC bus110by converting the nominal voltage of the low voltage DC bus150of the low voltage DC bus150into the nominal voltage of the high voltage DC bus110of the high voltage DC bus110. In a step-down mode of operation, the bidirectional DC/DC converter160is configured to provide power from the high voltage DC bus110to the low voltage DC bus150by converting the nominal voltage of the high voltage DC bus110of the high voltage DC bus110into the nominal voltage of the low voltage DC bus150of the low voltage DC bus150. In at least one embodiment, the bidirectional DC/DC converter160is electrically isolated from the high voltage DC bus110and the low voltage DC bus150, for example by way of transformers.

The hybrid power supply20further includes power electronics, in particular respective DC/DC converters, each configured to provide power from a respective one of the battery packs40A-C to the low voltage DC bus150. In at least some embodiments, these DC/DC converters are bidirectional DC/DC converters170A,170B,170C. In a discharge mode of operation, the DC/DC converters170A-C are configured to provide power from the battery pack(s)40A-C to the low voltage DC bus150by converting respective DC voltage(s) of the battery pack(s)40A-C, e.g., 18V or 36V, into the nominal voltage of the low voltage DC bus150. In a charge mode of operation, the DC/DC converters170A-C are configured to provide power from the low voltage DC bus150to the battery pack(s)40A-C by converting the nominal voltage of the low voltage DC bus150into the DC voltage necessary to charge each of the respective battery pack(s)40A-C. In at least one embodiment, the DC/DC converters170A-C are not electrically isolated.

In an alternative embodiment, shown inFIG.3, the low voltage DC bus150is omitted from the hybrid power supply20. In this embodiment, the bidirectional DC/DC converters170A,170B,170C connect directly to the high voltage DC bus110. Thus, in the discharge mode of operation, the DC/DC converters170A-C are instead configured to provide power from the battery pack(s)40A-C to the high voltage DC bus110by converting respective DC voltage(s) of the battery pack(s)40A-C, e.g., 18V or 36V, into the nominal voltage of the high voltage DC bus110. Likewise, in the charge mode of operation, the DC/DC converters170A-C are instead configured to provide power from the high voltage DC bus110to the battery pack(s)40A-C by converting the nominal voltage of the high voltage DC bus110into the DC voltage necessary to charge each of the respective battery pack(s)40A-C.

The power controller30is operably connected with the bidirectional AC/DC converter140, bidirectional DC/DC converter160, and the DC/DC converters170A-C and is configured to operate these power electronics to enable the first, second, third, fourth, and fifth operating modes of the hybrid power supply20. In some embodiments, the power controller30is a master controller and the hybrid power supply20includes respective slave controllers (not shown) in association with each of the bidirectional AC/DC converter140, bidirectional DC/DC converter160, and the DC/DC converters170A-C, and the power controller30commands the slave controllers to operate the bidirectional AC/DC converter140, bidirectional DC/DC converter160, and the DC/DC converters170A-C.

In the first operating mode, the power controller30is configured to operate the bidirectional AC/DC converter140to provide power from the AC power source50to the high voltage DC bus110. In this first operating mode, the loads of the power equipment10are provided with power from the AC power source50, via the high voltage DC bus110. Particularly, in some embodiments, a further controller (not shown) is configured to operate the high voltage motor drive130to drive high voltage motor120using power from the high voltage DC bus110.

In the second operating mode, the power controller30is configured to operate the DC/DC converter160and the DC/DC converters170A-C to provide power from the battery pack(s)40A-C to the high voltage DC bus110. In this second operating mode, the loads of the power equipment10are provided with power from the battery pack(s)40A-C, via the high voltage DC bus110. Particularly, in some embodiments, the further controller (not shown) is configured to operate the high voltage motor drive130to drive high voltage motor120using power from the high voltage DC bus110.

In the third operating mode, the power controller30is configured to operate the bidirectional AC/DC converter140and the DC/DC converter160to provide power from the AC power source50to the low voltage DC bus150. Additionally, in the third operating mode, the power controller30is configured to operate the DC/DC converters170A-C to charge the battery pack(s)40A-C using power from the low voltage DC bus150.

In the fourth operating mode, the power controller30is configured to operate the DC/DC converter160and the DC/DC converters170A-C to provide power from the battery pack(s)40A-C to the high voltage DC bus110. Additionally, in the fourth operating mode, the power controller30is configured to operate the bidirectional AC/DC converter140as a DC/AC inverter to provide AC power from the high voltage DC bus110to the AC accessory60connected to the hybrid power supply20.

In the fifth operating mode, the power controller30is configured to operate the bidirectional AC/DC converter140to provide power from the AC power source50to the high voltage DC bus110. Simultaneously, in the fifth operating mode, the power controller30is configured to operate the DC/DC converter160and the DC/DC converters170A-C to provide power from the battery pack(s)40A-C to the high voltage DC bus110. In this fifth operating mode, the loads of the power equipment10are provided with power from both the AC power source50and the battery pack(s)40A-C, via the high voltage DC bus110. Particularly, in some embodiments, the further controller (not shown) is configured to operate the high voltage motor drive130to drive high voltage motor120using power from the high voltage DC bus110.