Lightweight, compact, on-board electric vehicle battery charger

• US 6,087,802 A
• Filed: 08/24/1995
• Issued: 07/11/2000
• Est. Priority Date: 08/24/1995
• Status: Expired due to Fees

• Current Assignee: Coherent Power Limited
• Original Assignee: Coherent Power Limited
• Inventors: James, Ellen
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US08/518,638
• Time in Patent Office: 1,783 Days
• Field of Search: 320/2, 320/104, 323/266, 363/89, 363/124, 363/26
• US Class Current: 320/104
• CPC Class Codes: B60L 2210/14 Boost converters
• CPC Class Codes: B60L 53/14 Conductive energy transfer
• 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 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/4208 Arrangements for improving power factor of AC input
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y02T 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles

Abstract

An onboard electric vehicle charger is provided which incorporates a forward converter with dynamic balancing of the primary drive currents of its ferrite core transformer to produce 5,000 watt charging power with a power density of 333 watts per kilogram and full safety isolation between the input power source and the batteries plus small size (approximately 15" by 9" by 6") and weight (less than 15 kilograms) and a power factor correcting boost preregulator with dynamic adjustment of its compensation networks which produces full correction to substantially unity (99.9+%) for power factor with current total haromonic distortion (THD) of 2% to 3% over the entire power range of 100 watts to 5,000 watts. The same boost preregulator circuit allows operation from power sources of 95 to 145 VAC or 200 to 275 VAC. The combination of the boost converter, (boost preregulator) and forward converters with the invention'"'"'s control scheme enables constant throughput (in watts) during each step of the charging process and a constant pulse width modulation (PWM) duty cycle near maximum at all power levels by varying the output voltage of the boost preregulator in direct relation to the power level. A second forward converter, using the same dynamic balancing of primary currents utilized in the main forward converter described, works with the boost preregulator described to permit integration of a DC to DC converter function with 1 KW (75 A @ 14 VDC) capability plus full safety isolation between the high voltage propulsion batteries and the auxiliary (12 volt) electrical system of the vehicle.

Claims

1. An electric vehicle battery charger for charging a battery stack, comprising:

a connector sized and dimensioned to electrically couple the electric vehicle battery charger to a power source capable of providing power to the charger, the provided power comprising an input voltage and input current;

a boost pre-regulator receiving power from through the connector and having compensation networks which are dynamically adjusted for power level, the pre-regulator providing power factor correction to maintain a power factor of at least 99.9% and a total harmonic distortion of the input current of 2-3% at full power, and less than 5% at all power levels, while the input voltage is anywhere within the range of 95 to 265 VAC; and

a forward converter receiving cycle-by-cycle control from a current-mode controller which is in turn under the control of the boost pre-regulator, in order to achieve substantially constant duty cycle of the forward converter over the entire range of power levels.