Hong Kong Applied Science and Technology Research Institute Company, Limited

Po Wah Chang

Kwok Kuen (David) Kwong

Chik Wai (David) Ng

Wai Kit (Victor) So

Hing Kit Kwan

Yuanzhe Xu

Chi Chiu Tsang

Wai Kei Or

Shaobin Wu

A serial battery charger has a battery matrix with switches that are configured by a microcontroller that reads voltages between batteries to determine if each battery is fully-charged, charging, or absent. A switch configuration allows charging and discharging currents to flow simultaneously, and allows discharging current but blocks charging current from fully-charged batteries to prevent over-charging. The charging current flows through all charging batteries in series while the discharging current flows from all fully-charged and charging batteries in series. Blocking and bypass switches route the charging current to all charging batteries in series, but bypass all fully-charged and absent batteries. The blocking and bypass switches route the discharging current serially through all fully-charged and charging batteries in the battery matrix while avoiding absent batteries. The switches are controlled by the switch configuration from the microcontroller. Larger battery matrixes have row and column lines that are connected by connecting switches.

Serial multi-battery charger with independent simultaneous charge and discharge

A power converter reduces output ripple without using an electrolytic primary-side capacitor that can reduce product lifetime. Primary-Side Regulation (PSR) using an auxiliary winding provides a regulated secondary voltage with some low-frequency ripple on a secondary winding of a transformer. A smaller secondary capacitor that is not an electrolytic capacitor filters the output of the secondary side. A bang-bang controller controls the secondary side current to reduce current ripple despite voltage ripple. The bang-bang controller has a series resistor and inductor in series with a load such as an LED. A voltage drop across the series resistor increases when a switch turns on. This increasing voltage drop toggles the switch off once an upper limit voltage is reached. The voltage drop then decreases as inductor current is shunted by a diode, until the voltage drop reaches a lower limit voltage and the switch toggles on again.

LED driver with small output ripple without requiring a high-voltage primary-side electrolytic capacitor

Growing community of inventors

Hong Kong, China

Po Wah Chang