Switching circuit utilizing a field effect transistor and voltage regulator

Claim 2

A switching circuit as claimed in Claim I, characterised in that the control means (46) including means for permitting a change in state of the switching means (184) only substantially at a time when the charge circuit (170,172) is disabled and the discharge circuit (140,196) enabled.

Claim 3

A switching circuit as claimed in Claim I or Claim 2, characterised by means for sensing the gate bias voltage as the capacitor (116) discharges and for causing the switching means (184) to be biased conductive when the gate bias voltage decreases to a first predetermined value due to discharge of the capacitor to thereby cause the field effect transistor (38) to be biased nonconductive, and means responsive to the gate bias voltage decreasing to a second predetermined value for causing the charge circuit (170,172) to be re-enabled and the discharge circuit (140,196) disabled, the second predetermined value being less than the first predetermined value.

Claim 4

A switching circuit as claimed in any one of Claims I to 3, characterised by a conductor (120) connecting one end of the capacitor (116) to a junction (162), conductors (118,50) connecting the opposite end of the capacitor to the positive terminal of the voltage source (30), and a conductor - (40) connecting the junction to the gate (G).

Claim 5

A switching circuit as claimed in Claim 4, characterised in that the charge circuit for charging the capacitor (116) comprises a circuit (170,172) connected between the positive terminal of the voltage source (30) and the junction (162) and a second switching means (178) connected between the opposite end of the capacitor and the negative terminal of the voltage source, in that the means (13) responsive to the voltage across the capacitor attaining the predetermined charge voltage when the capacitor is charging biases the second switching means nonconductive to thereby disable the charge circuit; and in that the means (130) for sensing the gate bias voltage as the capacitor discharges causes the second switching means to be biased conductive to recharge the capacitor when the gate bias voltage decreases to the predetermined value.

Claim 6

A voltage regulator for a generator (10) that has an output winding (12) and a field winding (14) comprising, circuit means (16) having positive (22) and negative (24) direct voltage output terminals connected to the output winding, a field effect transistor (38) having a gate (G), a drain (D) and a source (S), conductors (39,36,26) connecting the drain to said positive direct voltage output terminal, and means connecting the field winding between the source of the field effect transistor and the negative direct voltage output terminal, characterised by a capacitor (116), a charging circuit (170,172) for charging the capacitor from the direct voltage output terminals, a discharging circuit (140,196) for discharging said capacitor, a voltage responsive control circuit (130) responsive to the magnitude of the voltage across the capacitor for disabling the charging circuit and enabling the discharging circuit when the voltage across the capacitor attains a predetermined value, means (130) responsive to the capacitor attaining said predetermined value of voltage for causing the direct voltage across the direct voltage output terminals to be added in series with the voltage across the capacitor to provide a gate bias voltage that is substantially the sum of the voltage across the direct voltage output terminals and the voltage attained by the capacitor and for applying the gate bias voltage to the gate to thereby provide a gate voltage that is high enough to bias the field effect transistor conductive between its drain and source, means (130) for sensing the gate bias voltage as the capacitor discharges and for causing the charging circuit to be re-enabled to recharge the capacitor when the gate bias voltage decreases to a predetermined value due to discharge of said capacitor, the predetermined value of gate bias voltage being high enough to maintain the field effect transistor biased conductive, a first switching means (184) connected between the gate of the field effect transistor and the negative terminal, the first switching means when conductive causing the field effect transistor to be biased nonconductive, and control means (46) controlling the switching state of the first switching means responsive to the output voltage of the generator for causing the first switching means to become or remain biased conductive when the output voltage of the generator is above a desired regulated value and for causing the first switching means to become or remain biased nonconductive when the output voltage is below the desired regulated value, the control means including means for permitting a change in state of the first switching means only substantially at a time when the charge circuit is disabled and the discharge circuit enabled.

Claim 7

A voltage regulator as claimed in Claim 6, characterised by a junction (162) a a conductor - (120) connecting an end of the capacitor (116) to the junction, conductors (118,50,36) connecting an opposite end of the capacitor to the positive direct- voltage input terminal (22), a conductor (40) connecting the junction to the gate (G); in that the charge circuit comprises a circuit (170,172) that is connected between the positive direct voltage input terminal and the junction and a second switching means (178) that is connected between the opposite end of the capacitor and the negative direct voltage input terminal (24), the capacitor charging through the second switching means when it is conductive; in that the voltage responsive control ciruit (130) is connected to the junction and biases the second switching means nonconductive to thereby disable the charge circuit, when the second switching means is biased nonconductive, in that the means (130) for sensing the gate bias voltage as the capacitor discharges causes the second switching means to be biased conductive to recharge the capacitor when the gate bias voltage decreases to the predetermined value, in that the first switching means (184) when nonconductive 'permits the gate bias voltage developed at the junction to bias the field effect transistor (38) conductive; and in that the control means (46) is responsive to the switching state of the second switching means.

Claim 8

A voltage regulator as claimed in Claim 7 wherein a resistor (42) is connected between the gate (G) and junction (162), the resistor and the gate capacitance of the field effect transistor (38) forming a filter circuit to smooth the voltage applied to the gate from the junction.

Claim 9

A voltage regulator as claimed in Claim 7 wherein the voltage regulator includes strobe control means responsive to the output voltage of the generator for shifting the voltage regulator into a strobing mode wherein the field effect transistor - (38) is biased conductive for consecutive occurring periods of time that have a predetermined duty cycle, the voltage regulator being shifted into the strobing mode when the output voltage of the generator (10) is zero or below a predetermined value, a third switching means (186) connected between the gate (G) and the negative direct voltage output terminal (24), the voltage regulator when in the strobing mode including means (194) operative to cause the third switching means to be biased conductive when said gate voltage decreases to a voltage level that is higher in voltage magnitude than the predetermined voltage value that causes the capacitor (116) to recharge during the time that the capacitor is discharging.

Claim 10

A voltage regulator as claimed in any one of Claims 7 to 9 characterised by means for repetitively charging and discharging the capacitor (116) and for causing the gate bias voltage that is developed at the junction (162) to be substantially equal to the sum of the capacitor voltage and the voltage across the positive and negative direct voltage output terminals (22,24) when capacitor charging is terminated and capacitor discharge begins, means for causing the capacitor to be recharged and capacitor discharge terminated when the gate bias voltage decreases to the predetermined value during discharge of the capacitor, the consecutive occurring charge and discharge periods of the capacitor being substantially equal to a timing period, the control means causing the field effect transistor (38) to be biased'conductive for a total time period that is substantially equal to the sum of a plurality of timing periods when the output voltage of the generator (10) is below the desired regulated value and for causing the field effect transistor to be biased nonconductive for a total time period that is substantially equal to the sum of a plurality of timing periods when the output voltage of the generator is above the desired regulated value.

Claim 11

II. A voltage regulator as claimed in Claim 10 wherein means are provided to cause the discharge period of the capacitor (116) to be shorter when the output voltage of the generator (10) is above the desired regulated value than it is when the generator output voltage is below the desired regulated value.

Claim 12

A voltage regulator as claimed in Claim 10 wherein the control means includes means for permitting a change in switching state of the field effect transistor (38) only substantially at a time when the capacitor charge period terminates and the capacitor discharge period begins.

Claim 13

A voltage regulator as claimed in any one of Claims 6 to 12 for use with a diode-rectified alternating current generator (10) that supplies the electrical loads on a motor vehicle including the charging of a storage battery (30) and comprises an alternating current generator (10) having a rotor driven by the engine (15), rectifier means (16) connected to the output winding (12) and having the positive and negative direct voltage output terminals (22,24), and a storage battery (30) connected across the direct voltage output terminals.