Shunt switched resistor regulator with diode snubber

Claim 2

A shunt switched resistor regulator power supply for supplying a variable amount of power to a load comprising: a rectifier means for accepting AC input voltage and converting it to DC output voltage at a positive and a negative terminal; first, second, third, and fourth nodes wherein said first and said fourth nodes are coupled to said positive and negative terminals, respectively; a current limiting resistor coupled between said first and second nodes; a capacitor coupled between said second and fourth nodes; a resistor having parasitic inductance coupled between said second and third nodes; a switch coupled between said third and fourth nodes; and a diode having its anode coupled to said third node and having its cathode coupled to said second node; means coupled to said load terminals for sensing the power being delivered to said load and for controlling said switch to have a duty cycle which results in the desired load current flowing through and a desired voltage appearing across said load in accordance with control input signals received at a control input.

Claim 3

A hybrid switched resistor regulator power supply for delivering a variable amount of power to a load comprising: a rectifier means for accepting AC input voltage and converting it to DC output voltage at a positive and a negative terminal; first, second, third, and fourth nodes wherein said first and said fourth nodes are coupled to said positive and negative terminals, respectively; a current limiting resistor coupled between said first and second nodes; means coupled between said first and said second nodes for selectively lowering the resistance between said first and second nodes when said power supply is to deliver more power to said load; a capacitor coupled between said second and fourth nodes; a resistor having parasitic inductance coupled between said second and third nodes; a switch coupled between said third and fourth nodes; and a diode having its anode coupled to said third node and having its cathode coupled to said second node; said third and fourth nodes being load terminals to which a load may be coupled; means coupled to said load terminals for sensing the power being delivered to said load and for controlling said switch to have a duty cycle which results in the desired load current flowing through and a desired voltage appearing across any said load coupled to said third and fourth nodes in accordance with control input signals received at a control input.

Claim 4

A hybrid switched resistor regulator power supply for delivering a variable amount of power to a load comprising: a rectifier means for accepting AC input voltage and converting it to DC output voltage at a positive and a negative terminal; first, second, third, and fourth nodes wherein said first and said fourth nodes are coupled to said positive and negative terminals, respectively; a current limiting resistor coupled between said first and second nodes; means coupled between said first and said second nodes for selectively lowering the resistance between said first and second nodes when said power supply is to deliver more power to said load; a capacitor coupled between said second and fourth nodes; a resistor having parasitic inductance coupled between said second and third nodes; a switch coupled between said third and fourth nodes; and a diode having its anode coupled to said third node and having its cathode coupled to said second node; said third and fourth nodes being load terminals to which a load may be coupled; means coupled to said load terminals for sensing the power being delivered to said load and for controlling said switch to have a duty cycle which results in the desired load current flowing through and a desired voltage appearing across any said load coupled to said third and fourth nodes in accordance with control input signals received at a control input.

Claim 5

The apparatus of claim 1 wherein said resistor having parasitic inductance is a wire wound resistor and wherein said switch is a transistor, and further comprising current shunt means coupled between said second and fourth nodes for providing a low resistance path for current flow between these nodes to reduce the voltage drop between these nodes lower than it would otherwise be absent said current shunt means when the duty cycle of said switch is substantially near 100% and said switch is on substantially all the time.

Claim 6

The apparatus of claim 2 wherein said resistor having parasitic inductance is a wire wound resistor and wherein said switch is a transistor, and further comprising current shunt means coupled between said first and second nodes for providing a low resistance path for current flow between these nodes to reduce the voltage drop between these nodes lower than it would otherwise be absent said current shunt means when the duty cycle of said switch is substantially near 100% and said switch is on substantially all the time.

Claim 9

A shunt switched resistor regulator comprising: a power source for supplying D.C. voltage; load terminals for coupling to a load; a means coupled between said power source and said load terminals for limiting current flow through any load coupled to said load terminals; power dissipation control means coupled across said load and responsive to a user input signal for controlling a variable amount of shunt current flow therethrough in accordance with a characteristic of said user input signal to control the power dissipation in the load, said power dissipation control means including a resistor having a parasitic inductance which is part of said resistor and a diode snubber coupled in parallel across said resistor with a polarity so as to conduct whenever a back electromotive force voltage transient arises in said parasitic inductance.

Claim 10

A shunt switched resistor regulator comprising: a power source for supplying D.C. voltage; load terminals for coupling to a load; a means coupled between said power source and said load terminals for limiting current flow through any load coupled to said load terminals; power dissipation control means coupled across said load and responsive to a user input signal for controlling a variable amount of shunt current flow therethrough in accordance with a characteristic of said user input signal to control the power dissipation in the load, said power dissipation control means including a resistor having a parasitic inductance which is part of said resistor and a diode snubber coupled in parallel across said resistor with a polarity so as to conduct whenever a back electromotive force voltage transient arises in said parasitic inductance.

Claim 11

An apparatus as defined in claim 6 further comprising a load capacitor coupled in parallel across said load terminals and means coupled to said power dissipation control means for providing a shunt current path of substantially zero resistance from said power source to said load terminal when said power dissipation control means is causing maximum power to be delivered to said load terminals.

Claim 12

A hybrid switched resistor regulator comprising: a power source for supplying D.C. voltage; load terminals for coupling to a load; means coupled between said power source and said load terminals for controlling the maximum amount of current that can flow through said load at any of several user selectable levels; power dissipation control means coupled across said load terminals and responsive to a user input signal for controlling a variable amount of shunt current flow therethrough in accordance with a characteristic of said user input signal to control the power dissipation in the load, said power dissipation control means including a resistor having a parasitic inductance which is part of said resistor and a diode snubber coupled in parallel across said resistor with a polarity so as to conduct whenever a back electromotive force voltage transient arises in said parasitic inductance.

Claim 13

A hybrid switched resistor regulator comprising: a power source for supplying D.C. voltage; load terminals for coupling to a load; means coupled between said power source and said load terminals for controlling the maximum amount of current that can flow through said load at any of several user selectable levels; power dissipation control means coupled across said load terminals and responsive to a user input signal for controlling a variable amount of shunt current flow therethrough in accordance with a characteristic of said user input signal to control the power dissipation in the load, said power dissipation control means including a resistor having a parasitic inductance which is part of said resistor and a diode snubber coupled in parallel across said resistor with a polarity so as to conduct whenever a back electromotive force voltage transient arises in said parasitic inductance.

Claim 14

The apparatus of claim 8 further comprising a load capacitor coupled across said load terminals and means coupled to said power dissipation control means for providing a shunt current path of substantially zero resistance from said power source to said load terminals when said power dissipation control means is causing maximum power to be delivered to said load terminals.

Claim 15

A power supply comprising: a rectifier; a pair of load terminals for coupling to a load; a resistor having parasitic inductance coupled to said rectifier and to said load terminals; switching means coupled to said resistor and having a control input for receiving a control signal indicating the desired power level to be dissipated in any said load coupled to said load terminals for switching current through said resistor in a manner so as to cause the amount of power dissipated in any said load to be in accordance with the desired power level; and a diode coupled across said resistor to shunt voltage transients in said parasitic inductance when current flow is shut off.

Claim 16

A power supply comprising: a rectifier; a pair of load terminals for coupling to a load; a resistor having parasitic inductance coupled to said rectifier and to said load terminals; switching means coupled to said resistor and having a control input for receiving a control signal indicating the desired power level to be dissipated in any said load coupled to said load terminals for switching current through said resistor in a manner so as to cause the amount of power dissipated in any said load to be in accordance with the desired power level; and a diode coupled across said resistor to shunt voltage transients in said parasitic inductance when current flow is shut off.

Claim 19

A method of operating a power supply as defined in claim 11 further comprising the steps of: sensing the actual power being delivered to the load; comparing the actual power being delivered to the load to the desired power; and adjusting the switching of current through said resistor to cause the desired level of power to be delivered to said load.

Claim 22

The method of claim 13 further comprising the steps of: sensing the desired level of power to be delivered to said load; sensing the actual level of power being delivered to said load; generating an error signal; using said error signal to make the necessary change in switching duty cycle of current switching through said resistor to adjust the actual power being delivered to said load to conform to the desired power to be delivered to said load.

Claim 23

The method of claim 14 further comprising the steps of limiting the maximum amount of current to be delivered to said load to some maximum with a current limiting device, but bypassing the current limiting device with a low resistance path during intervals when maximum power is to be delivered to said load.