Power converter for a thermal system
The present disclosure generally describes a system that includes a heater, a power converter including a power switch, and a controller. The power converter is in communication with the heater and is operable to apply an adjustable voltage to the heater. The controller is in communication with the power switch to control the voltage output of the power converter based on at least one of a load current and a detected voltage at the heater. The controller operates the power switch to adjust the voltage output of the power converter.
1. A thermal system comprising:
a heater comprising a resistive heating element operable to emit heat and operable as a sensor; and
a control system comprising:
a power converter being a step-down voltage converter and including a power switch, wherein the power converter is electrically coupled to the heater and is operable to apply an output voltage that is adjustable to the resistive heating element;
a sensor circuit configured to measure at least one of a voltage and an electric current of the resistive heating element; and
a controller connected to the power converter and the sensor circuit, the controller being configured to determine the output voltage applied to the resistive heating element based on an input parameter and a desired setpoint, wherein the controller is configured to operate the power switch of the power converter to apply the output voltage applied to the resistive heating element, and the input parameter includes a temperature of the resistive heating element that is determined based on the at least one of the voltage and the electric current, and the desired setpoint is based on an operational state of the heater.
2. The thermal system according to claim 1 , wherein the power converter includes a buck converter that includes the power switch.
3. The thermal system according to claim 1 , wherein the controller further comprises electronics having a microprocessor.
4. The thermal system according to claim 1 , wherein the power switch is a field effect transistor (FET).
5. The thermal system according to claim 1 , wherein the controller is configured to scale an input voltage to the heater based on one or more limits.
6. The thermal system according to claim 5 , wherein the one or more limits includes a sensed parameter value that includes at least one of voltage, current, and wattage.
7. The thermal system according to claim 1 , wherein the controller is configured to scale an input voltage to the heater to a value less than full line voltage.
8. The thermal system according to claim 1 , wherein the controller is configured to scale an input voltage to the heater between a preset minimum value and a preset maximum value.
9. The thermal system according to claim 1 , wherein the controller is configured to scale an input voltage to the heater based on a control algorithm.
10. The thermal system according to claim 9 , wherein the controller is configured to determine a resistance of the resistive heating element based on the at least one of the voltage and the electric current and scale the input voltage based on the resistance.
11. The thermal system according to claim 1 , wherein the controller is configured to scale an input voltage to the heater to limit amount of voltage applied to the heater.
12. The thermal system according to claim 1 further comprising a plurality of the heaters and a plurality of the power converters such that each of the plurality of the heaters is controlled by one or more power converters from among the plurality of the power converters.
13. The thermal system according to claim 1 , wherein the controller is configured to determine a resistance of the resistive heating element based on the at least one the voltage and the electric current and to execute diagnostics of the heater based on the resistance.
14. The thermal system according to claim 1 , wherein the controller is configured to operate the power converter to adjust the output voltage based on a resistance of the heater such that power from the power converter is proportional to a change in the resistance of the heater.
15. The thermal system according to claim 1 , wherein the controller is configured to switch the power switch at a selected duty cycle, and the duty cycle is directly proportional to a scaling factor.
16. The thermal system according to claim 1 , wherein the controller is configured to determine the temperature of the heater based on the at least one the voltage and the electric current, and switches the power switch at a selected duty cycle that is based on the temperature of the heater.
17. The thermal system according to claim 1 , wherein the desired setpoint includes a desired power to be applied to the heater.
18. The thermal system according to claim 1 , wherein the sensor circuit is configured to measure the voltage and the electric current of the resistive heating element, and the controller is configured to calculate a resistance of the heater based on the voltage and the current, and determines the temperature of the heater based on the resistance, further wherein the controller is configured to determine the output voltage based on the temperature of the heater.
19. A thermal system comprising:
a heater having a plurality of resistive heating elements, wherein each of the resistive heating elements is operable to emit heat and operable as a sensor; and
a control system comprising:
a plurality of power converters, each of the plurality of power converters being a step-down voltage converter that includes a power switch, wherein a given power converter from among the plurality of power converters is electrically coupled to one or more resistive heating elements from among the plurality of resistive heating elements, wherein the given power converter is operable to apply an output voltage that is adjustable to the one or more resistive heating elements;
a plurality of sensor circuits, wherein each of the plurality of sensor circuits includes a current sense resistor, a given sensor circuit from among the plurality of sensor circuits is electrically coupled between the given power converter and the one or more resistive heating elements from among the plurality of resistive heating elements and the given sensor circuit is configured to measure at least one of a voltage and an electric current of the one or more resistive heating elements from among the plurality of resistive heating elements; and
a controller connected to the plurality of power converters and the plurality of sensor circuits, wherein, for the given power converter, the controller is configured to determine the output voltage applied to the one or more resistive heating elements based on an input parameter and a desired setpoint and to operate the power switch of the given power converter to apply the output voltage to the one or more resistive heating elements, wherein the input parameter includes a temperature of the one or more resistive heating elements that is determined based on the at least one of the voltage and the electric current measured by the given sensor circuit, and the desired setpoint is based on an operational state of the heater.
20. The thermal system according to claim 19 , wherein the controller is configured to calculate resistances of the plurality of resistive heating elements and determine the temperature of the heater based on the resistances of the plurality of resistive heating elements and adjust the temperature to compensate for a leakage current from the power switches.
21. The thermal system according to claim 19 , wherein the controller is configured to determine the temperature of the heater based on the resistance, and the controller is configured to control the output voltage of one or more of the power converters from among the plurality of power converters based on the temperature of the heater.