Control system for powering plural inductive loads from a single inverter source
First Claim
1. A control system for controlling overshoot and undershoot power values when switching power from an output of a single inverter power supply to at least a selected one of plural inductive loads, each inductive load having a respective resonant frequency associated therewith, the inverter power supply having an inverter output switch therein and being adjustable for outputting a preselected amount of power, the system comprising:
- (a) load switching means for selectably switching the inverter output among selected ones of the plural inductive loads in a time-shared manner;
(b) means for measuring power output from the inverter and detecting overshoot or undershoot power values occurring when switching from one inductive load to another;
(c) time delay source for connection to the load switching means for starting a delay time period upon switching from one inductive load to another and for generating and outputting a signal at a preselected end of said delay time period, the signal triggering the inverter output switch to deliver the power output of the inverter to the load switching means for switching to the selected load; and
(d) means for adjusting the preselected end of the delay time period during a subsequent switching operation from one load to another in response to the measured overshoot or undershoot power values by an amount calculated to reduce subsequent power overshoot or undershoot.
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Accused Products
Abstract
A control system for controlling overshoot and undershoot power values when switching power from a single inverter power source to a plurality of inductive loads, or a single load having a plurality of zones, having different resonant frequencies. The control system causes a preselected amount of power to be drawn from the inverter power source and delivered to the loads, or zones in a time-shared manner. The control system varies the phase shift between load voltage and load current and selectably adjusts the amount of variation in response to overshoot and/or undershoot of power drawn from the inverter and delivered to a load or zone which can occur when switching between loads or zones.
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Citations
32 Claims
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1. A control system for controlling overshoot and undershoot power values when switching power from an output of a single inverter power supply to at least a selected one of plural inductive loads, each inductive load having a respective resonant frequency associated therewith, the inverter power supply having an inverter output switch therein and being adjustable for outputting a preselected amount of power, the system comprising:
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(a) load switching means for selectably switching the inverter output among selected ones of the plural inductive loads in a time-shared manner; (b) means for measuring power output from the inverter and detecting overshoot or undershoot power values occurring when switching from one inductive load to another; (c) time delay source for connection to the load switching means for starting a delay time period upon switching from one inductive load to another and for generating and outputting a signal at a preselected end of said delay time period, the signal triggering the inverter output switch to deliver the power output of the inverter to the load switching means for switching to the selected load; and (d) means for adjusting the preselected end of the delay time period during a subsequent switching operation from one load to another in response to the measured overshoot or undershoot power values by an amount calculated to reduce subsequent power overshoot or undershoot. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 31)
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12. A control system for controlling overshoot and undershoot power values when switching power in a pulse width modulation manner from an output of a single inverter source to plural inductive loads, each inductive load having a respective resonant frequency, the inverter source set for outputting a set amount of power, the system comprising:
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(a) inductive load switching means for switching to successive inductive loads, the inverter output being connected to the switching means for directing the inverter output to the successive inductive loads; (b) an inverter output switch associated with the inverter source; (c) means for measuring a maximum amount of overshoot and/or undershoot of power which occurs when switching to a successive inductive load, the overshoot and/or undershoot representing drawing by the load of an amount of power greater or less than the amount of power set for outputting by the inverter; (d) time delay source for connection to the inductive load switching means for starting a time period upon detection of the switching to a successive load and for generating and outputting a signal at the end of a preselected time period, the signal triggering the inverter output switch to deliver the inverter'"'"'s power to the successive load; and (e) means for adjusting the preselected time period in response to the maximum measured amount of overshoot and/or undershoot, the adjustment occurring during a subsequent switching to the successive loads, thereby reducing subsequent amounts of overshoot and/or undershoot. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 32)
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23. A method for controlling the power overshoot and undershoot when switching power in a pulse width modulation manner from an output of a single inverter source to plural inductive loads, each inductive load having a respective resonant frequency, the inverter source set for outputting a set amount of power, the method comprising the steps of:
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(a) during a first switching cycle (i) presetting an initial time delay value which represents the time between when a respective load is switched to receive the inverter source power and when the inverter source is triggered to actually provide the power; (ii) measuring a maximum amount of overshoot and/or undershoot which occurs when switching to a successive load, the overshoot and/or undershoot representing drawing by the load of an amount of power greater or less than the amount of power set for outputting by the inverter; (iii) determining a time delay value for each load which will correct the overshoot and/or undershoot; (iv) loading the time delay values for each load into a memory; and (b) during subsequent switching cycles (i) retrieving the time delay values upon switching of the respective load to receive the inverter source power; and (ii) setting a new time delay value using the value for the respective load, thereby reducing subsequent amounts of overshoot and/or undershoot. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
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Specification