Dual voltage charging system

• US 4,047,088 A
• Filed: 06/09/1976
• Issued: 09/06/1977
• Est. Priority Date: 06/09/1976
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Himmler, Dennis W.
• Primary Examiner(s): Hickey, Robert J.
• Application Number:
  US05/694,158
• Time in Patent Office: 454 Days
• Field of Search: 320/6, 320/15, 320/16, 320/17, 320/39, 320/40, 322/89, 322/90, 322/94
• US Class Current: 320/123
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y10S 320/25 Optical coupler

Abstract

A motor vehicle electrical system which is capable of supplying both 12 and 24 volt loads. A pair of 12 volt batteries are permanently connected in series and are charged in series under certain conditions of operation from a 24 volt charging system including an alternating current generator and a bridge rectifier. The output voltage of the 24 volt charging system is maintained substantially constant by a voltage regulator connected with the field of the generator which senses and responds to the output voltage of the bridge rectifier that is applied to the series connected batteries and other 24 volt loads. An auxiliary charging circuit is provided connected between one of the phase windings of the generator and the junction of the series connected batteries for, at times, supplying current to one of the batteries that supplies the 12 volt loads. This circuit includes a series connected silicon controlled rectifier and inductance. The controlled rectifier is gated into conduction whenever the voltage at the junction of the two batteries drops below a voltage corresponding substantially to one-half of the output voltage of the bridge rectifier that feeds the 24 volt loads.

Claims

1. A motor vehicle electrical system comprising, an alternating current generator having a polyphase output winding and a field winding, a polyphase full-wave bridge rectifier having AC input terminals and direct voltage output terminals, means connecting said output winding with said AC input terminals of said bridge rectifier, positive and negative power supply conductors connected respectively with said direct voltage output terminals, first and second batteries, means connecting said batteries in series across said power supply conductors whereby said batteries can be charged at times in series by the direct voltage output of said bridge rectifier, the negative terminal of one battery connected to the positive terminal of the other battery, the connection between said batteries defining a battery junction having a voltage intermediate the voltage of said power supply conductors, voltage regulating means including voltage sensing means connected across said power supply conductors and a field current control means for controlling field current as a function of the voltage sensed by said sensing means to thereby maintain the voltage across said power supply conductors substantially constant, voltage divider means connected across said power supply conductors having a voltage divider junction that has a voltage intermediate the voltage of said power supply conductors, the ratio of voltage division provided by said voltage divider means being substantially equal to the ratio of the terminal voltage ratings of said batteries whereby said voltage divider junction and said battery junction have substantially equal voltages during certain conditions of operation of said system, a circuit connected between one phase winding of said output winding and said battery junction for at times supplying charging current to said second battery, said circuit comprising in a series connection an inductive circuit element and the anode-cathode circuit of a first controlled rectifier, a second controlled rectifier having an anode connected to said one phase winding and a cathode connected to the gate of said first controlled rectifier, said second controlled rectifier operative to gate said first controlled rectifier conductive when said second controlled rectifier is gated conductive, and means coupled to said battery and voltage divider junctions and to said second controlled rectifier for gating said second controlled rectifier conductive when the voltage at said voltage divider terminal exceeds the voltage at said battery terminal by a predetermined amount, said first controlled rectifier being nonconductive when the voltage at said battery terminal is substantially equal to or greater than the voltage of said voltage divider junction.

2. A motor vehicle electrical system comprising, an alternating current generator having a three-phase output winding and a field winding, a polyphase bridge rectifier circuit having AC input terminals connected to said output winding and direct voltage output terminals, a positive direct voltage power supply conductor connected with the positive direct voltage output terminal of said bridge rectifier, a negative power supply conductor connected to the negative direct voltage output terminal of said bridge rectifier, first and second batteries having substantially equal voltage ratings, means connecting said batteries in series with each other and across said power supply conductors, the negative terminal of one of said batteries being connected to the positive terminal of the other battery, the connection between said batteries defining a battery junction having a voltage intermediate the voltage of said power supply conductors, voltage regulating means including field current control means connected with said field winding for controlling field current, said voltage regulating means including a voltage sensing means connected across said power supply conductors and operative to control said field current control means so as to maintain a substantially constant voltage between said power supply conductors, voltage divider means having a voltage divider junction connected across said power supply conductors, said voltage divider means being so proportioned as to provide a voltage at said voltage divider junction which is substantially equal to one-half the voltage appearing across said power supply conductors, a circuit connected between one end of one of the phase windings and said battery junction for supplying current to said second battery, said circuit comprising in a series connection an inductive circuit element and the anode-cathode circuit of a first controlled rectifier, a second controlled rectifier having an anode connected to said one end of said phase winding and a cathode connected to the gate of said first controlled rectifier, said second controlled rectifier operative to gate said first controlled rectifier conductive when said second controlled rectifier is gated conductive, and means connected with said voltage divider and battery junctions and coupled to said second controlled rectifier for gating said second controlled rectifier conductive when the voltage at said voltage divider junction exceeds the voltage of said battery junction, said first controlled rectifier being nonconductive when the voltage of said battery junction substantially equals or is greater than the voltage of said voltage divider junction.

3. A motor vehicle electrical system comprising, an alternating current generator having a polyphase output winding and a field winding, a full-wave bridge rectifier having positive and negative direct voltage output terminals, positive and negative power supply conductors connected respectively with the positive and negative direct voltage output terminals of said bridge rectifier, first and second batteries having substantially equal terminal voltages, means connecting the positive terminal of said first battery to said positive power supply conductor, means connecting the negative terminal of said second battery to said negative power supply conductor, means connecting the negative terminal of said first battery to the positive terminal of said second battery whereby said batteries are connected in series across said power supply conductors, a battery junction connected to the negative terminal of said first battery and to the positive terminal of said second battery, voltage regulating means sensing the voltage across said power supply conductors and connected to said field winding for maintaining the voltage across said power supply conductors at a desired regulated value, an auxiliary charging circuit for said second battery connected between one phase winding of said output winding and said battery junction, said circuit comprising in a series connection a circuit element having inductance and the anode and cathode of a first controlled rectifier, said circuit element connected between said one phase winding and the anode of said first controlled rectifier, a second light actuated controlled rectifier having its anode connected between said circuit element and the anode of said first controlled rectifier and having its cathode connected to the gate of said first controlled rectifier, a light-emitting diode optically coupled to said light actuated controlled rectifier operative to trigger said light actuated controlled rectifier conductive when said light-emitting diode is energized, means connected across said power supply conductors for developing a reference voltage which is substantially equal to one-half the voltage appearing across said power supply conductors, an operational amplifier having an output connected to said light-emitting diode, means for applying said reference voltage to one input of said operational amplifier, and means connecting said battery junction to another input of said operational amplifier, said operational amplifier operative to energize said light-emitting diode when said reference voltage exceeds the voltage of said battery junction.