Control system for an electrocaloric device

Patent metadata

Field	Value
Publication number	US-11187441-B2
Application number	US-201916598582-A
Country	US
Kind code	B2
Filing date	Oct 10, 2019
Priority date	Oct 10, 2019
Publication date	Nov 30, 2021
Grant date	Nov 30, 2021

Abstract

A method for operating an electrocaloric system includes determining an internal temperature lift of an electrocaloric device. A current temperature of a space to be cooled is determined. A heat rejection temperature is determined. A difference between the current temperature and the heat rejection temperature is determined. A target temperature lift is determined based on the difference and a target temperature for the space. A voltage applied to the electrocaloric device is modulated based on the internal temperature lift and the target temperature lift.

First claim

The invention claimed is:

1. A method for operating an electrocaloric system, comprising:
determining an internal temperature lift of an electrocaloric device;
determining a current temperature of a space to be cooled;
determining a heat rejection temperature;
determining a difference between the current temperature and the heat rejection temperature;
determining a target temperature lift based on the difference and a target temperature for the space; and
modulating a voltage applied to the electrocaloric device based on the internal temperature lift and the target temperature lift.

2. The method of claim 1 , wherein determining the internal temperature lift of the electrocaloric device comprises measuring at least two temperatures at different locations of the electrocaloric device.

3. The method of claim 1 , wherein determining the internal temperature lift of the electrocaloric device is based on the voltage applied to the electrocaloric device.

4. The method of claim 1 , wherein determining the heat rejection temperature comprises measuring a temperature at a location that heat is rejected.

5. The method of claim 1 , wherein determining the heat rejection temperature comprises determining the heat rejection temperature based on current weather data.

6. The method of claim 1 , wherein determining the target temperature lift comprises determining a difference between a thermostat setpoint and the heat rejection temperature.

7. The method of claim 1 , wherein modulating the voltage applied to the electrocaloric device comprises setting a switching voltage on the electrocaloric device such that the determined internal temperature lift is greater than or substantially equal to the target temperature lift.

8. The method of claim 1 , further comprising:
receiving an input from a user indicating that fast cooling is requested; and
increasing a switching voltage based on the user input.

9. The method of claim 1 , further comprising:
establishing a target temperature band; and
after the target temperature is reached, applying a voltage to the electrocaloric device that is as low as possible while maintaining the target temperature band.

10. The method of claim 9 , wherein the target temperature band is based on one or more of factory settings and user input.

11. The method of claim 1 , further comprising determining a heat load of the space to be cooled.

12. The method of claim 11 , wherein determining the heat load of the space comprises measuring a rate of temperature change of one or more of the electrocaloric device and a rate of temperature change of the space.

13. The method of claim 11 , further comprising, modulating a switching frequency of the electrocaloric device based on the heat load of the space to be cooled.

14. The method of claim 13 , wherein modulating the switching frequency comprises modulating an operating frequency after the target temperature is reached.

15. The method of claim 13 , wherein modulating the switching frequency is done concurrently with modulating the voltage applied to the electrocaloric device.

16. The method of claim 11 , further comprising:
receiving an input from a user indicating that fast cooling is requested; and
increasing a switching frequency of the electrocaloric device based on the user input.

17. The method of claim 11 , further comprising:
establishing a target temperature band; and
after the target temperature is reached, maintaining a switching frequency of the electrocaloric device that is as low as possible while maintaining the target temperature band.

18. The method of claim 11 , wherein determining the internal temperature lift comprises determining the internal temperature lift based on one or more of the heat load of the space to be cooled and the voltage applied to the electrocaloric device.

19. An electrocaloric system, comprising:
an electrocaloric device;
a voltage source configured to apply a voltage to the electrocaloric device; and
a controller configured to:
determine an internal temperature lift of the electrocaloric device;
determine a current temperature of a space to be cooled;
determine a heat rejection temperature;
determine a difference between the current temperature and the heat rejection temperature;
determine a target temperature lift based on the difference and a target temperature for the space; and
modulate the voltage applied to the electrocaloric device based on the internal temperature lift and the target temperature lift.

20. The electrocaloric system of claim 19 , further comprising a user interface configured to receive input from a user.

21. The electrocaloric system of claim 19 , wherein the controller is configured to modulate the voltage applied to the electrocaloric device by setting a switching voltage on the electrocaloric device such that the determined internal temperature lift is greater than or substantially equal to the target temperature lift.

22. An electrocaloric system, comprising:
an electrocaloric device;
a voltage source configured to apply a voltage to the electrocaloric device at a switching frequency; and
a controller configured to:
measure a rate of temperature change of one or more of an electrocaloric device and a rate of temperature change of a space to be cooled;
determine a heat load of the space to be cooled based on the measured rate of temperature change; and
modulate the switching frequency of the electrocaloric device based on the heat load of the space to be cooled.

Assignees

• Palo Alto Res Ct Inc

Inventors

• Schwartz David E

Classifications

• F25B21/00 Primary

  Machines, plants or systems, using electric or magnetic effects · CPC title

• Y02B30/00

  Energy efficient heating, ventilation or air conditioning [HVAC] · CPC title

• F25B2321/001

  by using electro-caloric effects · CPC title

• F25B2600/00

  Control issues · CPC title

• F25B49/00

  Arrangement or mounting of control or safety devices · CPC title