BATTERY CHARGER

• US 20180219474A1
• Filed: 06/30/2016
• Published: 08/02/2018
• Est. Priority Date: 07/21/2015
• Status: Abandoned Application

• Current Assignee: Dyson Technology Limited (Beeswax Holdings UK Limited)
• Original Assignee: Dyson Technology Limited (Beeswax Holdings UK Limited)
• Inventors: GREETHAM, Stephen, BERRY, Stephen, KOTTE, Hari Babu, RADHIKA, Ambatipudi
• Application Number:
  US15/746,248
• Publication Number:
  US 20180219474A1
• Time in Patent Office: Days
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 1/083 for the ignition at the zero crossing of the voltage or the current
• CPC Class Codes: H02M 1/12 Arrangements for reducing harmonics from ac input or output
• CPC Class Codes: H02M 1/4208 Arrangements for improving power factor of AC input
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H02M 1/4241 using a resonant converter
• CPC Class Codes: H02M 1/4258 using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage H02M1/4241 takes precedence
• CPC Class Codes: H02M 3/33576 having at least one active switching element at the secondary side of an isolation transformer
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Abstract

A battery charger comprising input terminals for connection to an AC source, output terminals for connection to a battery to be charged, and a power factor correction (PFC) circuit connected between the input terminals and the output terminals. The PFC circuit comprises a current control loop for regulating an input current drawn from the AC source. The voltage at the output of the PFC circuit is regulated by the voltage of the battery which is reflected back to the PFC circuit. As a result, the battery charger acts as a current source that outputs an output current at the output terminals, and the waveform of the output current is periodic with a frequency twice that of the input current and a ripple of at least 50%.

Claims

1. A battery charger comprising input terminals for connection to an AC source, output terminals for connection to a battery to be charged, and a power factor correction (PFC) circuit connected between the input terminals and the output terminals, wherein the PFC circuit comprises a current control loop for regulating an input current drawn from the AC source, wherein a voltage at the output of the PFC circuit is regulated by a voltage of the battery which is reflected back to the PFC circuit such that the battery charger acts as a current source that generates an output current at the output terminals, and wherein a waveform of the output current is periodic with a frequency twice that of the input current and a ripple of at least 50%.

2. The battery charger of claim 1, wherein the PFC circuit comprises a capacitor, and the capacitor is held at a voltage that is proportional to the voltage of the battery.

3. The battery charger of claim 1, wherein the PFC circuit adjusts an average value of the input current in response to one or more changes in the voltage of the battery.

4. The battery charger of claim 3, wherein the PFC circuit increases the average value of the input current in response to an increase in the voltage of the battery.

5. The battery charger of claim 3, wherein the PFC circuit adjusts the average value of the input current in response to changes in the voltage of the battery such that the average value of the output current is constant.

6. The battery charger of claim 1, wherein the battery charger operates in a first mode when the voltage of the battery is less than a threshold, the battery charger switches to a second mode when the voltage of the battery exceeds the threshold, the AC source supplies an alternating input voltage, the PFC circuit causes the input current to be drawn from the AC source during each half-cycle of a plurality of half-cycles of the input voltage when operating in the first mode, and the PFC circuit causes the input current to be drawn from the AC source during only some of the half-cycles of the input voltage when operating in the second mode.

7. The battery charger of claim 1, wherein the AC source supplies an alternating input voltage, and the battery charger comprises a step-down DC-to-DC converter having a voltage conversion ratio greater than a peak value of the input voltage divided by a minimum voltage of the battery.

8. The battery charger of claim 1, wherein the battery charger comprises a step-down DC-to-DC converter having one or more primary-side switches that are switched at a constant frequency.

9. The battery charger of claim 8, wherein the DC-to-DC converter has one or more secondary-side switches that are switched at the same constant frequency.