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US-20260128598-A1 - BATTERY PACK CHARGER WITH A HYBRID FLYBACK CONVERTER

US20260128598A1US 20260128598 A1US20260128598 A1US 20260128598A1US-20260128598-A1

Abstract

A battery pack charger having housing including a battery pack interface for removably receiving a battery pack and a power input. The battery pack charger including a hybrid flyback converter having a primary side including a DC-DC half-bridge and a secondary side including a synchronous rectifier. The hybrid flyback converter is electrically connected between the power input and the battery pack interface and is configured to provide charging power from the power input to the battery pack interface.

Inventors

  • Nicholas S. Brucks
  • Vivek S. Nagal
  • Paul C. Chao

Assignees

  • MILWAUKEE ELECTRIC TOOL CORPORATION

Dates

Publication Date
20260507
Application Date
20251106

Claims (20)

  1. 1 . A battery pack charger comprising: a housing; a power input; a battery pack interface provided on the housing and configured to removably receive a battery pack; a hybrid flyback converter (HFC) having a primary side including a DC-DC half bridge and a secondary side including a synchronous rectifier electrically connected between the power input and the battery pack interface, the HFC configured to provide charging power from the power input to the battery pack interface; and a controller electrically connected to the HFC and configured to control an amount of power provided on the secondary side.
  2. 2 . The battery pack charger of claim 1 , further comprising: an input rectifier electrically connected between the power input and the HFC, the input rectifier configured to convert AC power from the power input to DC power, wherein the DC power is provided to the HFC.
  3. 3 . The battery pack charger of claim 2 , wherein the HFC includes a plurality of switches, and wherein the controller is configured to control the plurality of switches to convert DC power between the power input and the battery pack interface.
  4. 4 . The battery pack charger of claim 3 , further comprising a power factor correction (PFC) boost converter electrically connected between the input rectifier and the DC-DC half bridge of the hybrid flyback converter.
  5. 5 . The battery pack charger of claim 4 , wherein the controller includes a single controller to control the PFC boost converter and the HFC converter provided on a single chip.
  6. 6 . The battery pack charger of claim 1 , wherein the synchronous rectifier includes at least one switch, wherein the at least one switch is a MOSFET.
  7. 7 . The battery pack charger of claim 1 , further comprising a fan provided within the housing and configured to cool electronics within the housing and/or the battery pack.
  8. 8 . The battery pack charger of claim 7 , further comprising: an AC current sensor provided in a current path between the power input and the battery pack interface; and a fan control circuit electrically connected to the AC current sensor and configured to control the fan based on AC current measured by the AC current sensor.
  9. 9 . The battery pack charger of claim 1 , wherein the battery pack interface is a first-type battery pack interface configured to receive a first-type battery pack, further comprising a second-type battery pack interface provided on the housing and configured to receive a second-type battery pack of a different type than the first-type battery pack.
  10. 10 . The battery pack charger of claim 9 , wherein the first-type battery pack having a nominal voltage of 18V and the second-type battery pack having a nominal voltage of 12V.
  11. 11 . The battery pack charger of claim 1 , further comprising a plurality of battery pack interfaces on the housing, the plurality of battery pack interfaces split into groups, each group including at least two battery pack interfaces.
  12. 12 . The battery pack charger of claim 11 , wherein a first group includes a plurality of first-type battery pack interfaces, and a second group includes a plurality of first-type battery pack interfaces and one second-type battery pack interface.
  13. 13 . The battery pack charger of claim 12 , wherein only one battery pack in each group charges at a time.
  14. 14 . The battery pack charger of claim 1 , wherein a total power output of the battery pack charger is 760 Watts.
  15. 15 . A battery pack charger comprising: a housing including a battery pack interface configured to removably receive a battery pack; a power input; a power circuit electrically connected between the power input and the battery pack interface and configured to provide charging power from the power input to the battery pack interface; a fan provided within the housing and proximate the battery pack interface; an AC current sensor electrically connected between the power input and an input of the power circuit, the AC current sensor configured to measure an AC current; and a fan control circuit electrically connected to the AC current sensor and the fan, the fan control circuit configured to control the fan based on the AC current.
  16. 16 . The battery pack charger of claim 15 , wherein the fan control circuit is configured to enable the fan when the AC current exceeds a first threshold.
  17. 17 . The battery pack charger of claim 16 , wherein the fan control circuit is configured to disable the fan when the AC current fall below a second threshold and the fan is enabled.
  18. 18 . The battery pack charger of claim 17 , wherein the AC current is measured as a root mean square (RMS) current, the first threshold is 2 ARMS, and the second threshold is a hysteresis amount below the first threshold.
  19. 19 . A method of controlling a fan for a battery pack charger, the method comprising: measuring an RMS AC current with an AC current sensor electrically connected between a power input of the battery pack charger and a battery pack interface of the battery pack charger, the battery pack interface configured to removably receive a battery pack; enabling the fan when the RMS AC current exceeds a first threshold; and disabling the fan when the RMS AC current subsequently drops below a second threshold.
  20. 20 . The method of claim 19 , wherein the second threshold is lower than the first threshold.

Description

RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63/717,541, filed November 7, 2024, the entire content of which is incorporated herein by reference. FIELD The present disclosure relates to a converter assembly and particularly to a hybrid flyback converter for a battery pack charger. SUMMARY Certain power tools operate using battery packs as their primary power source. The type of battery pack used varies depending on the power requirements of the specific power tool. Using a single charger capable of accommodating multiple battery types offers advantages in terms of space efficiency, cost savings, and convenience. To support faster charging across various battery types, the system may need to deliver increased total current. However, higher charging current can lead to elevated temperatures. Fans may be used to regulate the temperature of both the electronic components of the charger and the battery packs.. In some aspects, the techniques described herein relate to a battery pack charger including: a housing; a power input; a battery pack interface provided on the housing and configured to removably receive a battery pack; a hybrid flyback converter (HFC) having a primary side including a DC-DC half bridge and a secondary side including a synchronous rectifier electrically connected between the power input and the battery pack interface, the HFC configured to provide charging power from the power input to the battery pack interface; and a controller electrically connected to the HFC and configured to control an amount of power provided on the secondary side. In some aspects, the techniques described herein relate to a battery pack charger including: a housing including a battery pack interface configured to removably receive a battery pack; a power input; a power circuit electrically connected between the power inpuit and the battery pack interface and configured to provide charging power from the power input to the battery pack interface; a fan provided within the housing and proximate the battery pack interface; an AC current sensor electrically connected between the power input and an input of the power circuit, the AC current sensor configured to measure an AC current; and a fan control circuit electrically connected to the AC current sensor and the fan, the fan control circuit configured to control the fan based on the AC current. In some aspects, the techniques described herein relate to a method of controlling a fan for a battery pack charger, the method including: measuring an RMS AC current with an AC current sensor electrically connected between a power input of the battery pack charger and a battery pack interface of the battery pack charger, the battery pack interface configured to removably receive a battery pack; enabling the fan when the RMS AC current exceeds a first threshold; and disabling the fan when the RMS AC current subsequently drops below a second threshold. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an example battery pack charger of according to some aspects of the disclosure herein. FIG. 2 illustrates an example of a first-type battery pack receivable in the example battery pack charger of FIG. 1 according to some aspects of the disclosure herein. FIG. 3 illustrates an example of a second-type battery pack receivable in the example battery pack charger of FIG. 1 according to some aspects of the disclosure herein. FIG. 4 illustrates a block diagram of an example configuration of a battery pack charger according to some aspects of the disclosure herein. FIG. 5 illustrates a main power circuit board assembly with a converter assembly according to some aspects of the disclosure herein. FIG. 6 illustrates a block diagram for the converter assembly from FIG. 5 according to some aspects of the disclosure herein. FIG. 7 illustrates a diagram of an example DC-DC half bridge used in the converter assembly of FIG. 6 according to some aspects of the disclosure herein. FIG. 8 illustrates a block diagram of a low power auxiliary rail from the converter assembly of FIG. 6 according to some aspects of the disclosure herein. FIG. 9 illustrates a block diagram of an example configuration of a battery pack charger with a fan according to some aspects of the disclosure herein. FIG. 10 illustrates a flow chart for a method of controlling the fan from FIG. 5 according to some aspects of the disclosure herein. FIG. 11 illustrates a first group configuration for the battery pack charger of FIG. 1 according to some aspects of the disclosure herein. FIG. 12 illustrates a second group configuration for the battery pack charger of FIG. 1 according to some aspects of the disclosure herein. FIG. 13 illustrates a flow chart of a method of controlling a fan for the battery pack charger of FIG. 1 according to some aspects of the disclosure herein. Before any examples of the disclosure are explained in detail, it is to be understood that the disclosure i