Wireless control and status monitoring for electric grill with current protection circuitry
Provided is an apparatus and method for protecting against unsafe electric current conditions. A protections circuit may be used in a device, such as an electric grill, that has one or more electric loads, such as heating elements. The protection circuit may protect against various failure scenarios, including, without limitation, instances of ground fault, over current, driver failure, and failure of a microprocessor. The microprocessor may further be in wireless communication with a remote device and wirelessly communicate error codes indicative of an error, and receive control signals from the remote device for controlling temperature or turning the grill off. The remote device may also receive operating parameters and create a log of the electric grill's conditions at the time of an error.
1. A system for monitoring a status of an electric grill, the system comprising:
a heating element connected to a voltage line through at least one triac, the at least one heating element connected to a neutral line;
a user input device for selecting a high, medium, or low operating mode of the at least one heating element;
a latch connected between the heating element and the voltage line, the latch connected to a trip controller through a control line;
a cooking surface;
a temperature sensing device for measuring temperature at a first position inside a cook box of the electric grill, the temperature sensing device positioned on a first side of a plane defined by the cooking surface, the heating element positioned on the first side of the plane defined by the cooking surface;
a Hall Effect sensor configured to measure current delivered to the heating element;
a ground fault detection unit configured to detect a ground fault error between the voltage line and the neutral line;
a current transformer to measure a difference in current between the voltage line and the neutral line, the current transformer connected through the control line to the ground fault detection unit;
a wireless controller; and
a microprocessor in communication with a memory, the user input device, the Hall Effect sensor, the ground fault detection unit, the temperature sensing device, and the wireless controller, wherein the microprocessor is to:
receive a measured electrical current from the Hall Effect sensor;
access the memory to retrieve an expected electrical current associated with the selected high, medium, or low operating mode of the heating element, the expected electrical current being an electrical current reading expected during normal operating conditions in said operating mode;
calculate an estimated ambient temperature at a second position within the cook box based on the measured temperature at the first position, the second position located on a second side of the plane defined by the cooking surface, the second side of the plane opposite the first side of the plane;
detect an error condition by comparing the measured electrical current to the expected electrical current;
disable the latch to prevent the flow of current to the heating element in response to a measured electrical current that is higher or lower than the expected electrical current;
respond to a detected error condition by adding an entry to an error log in the memory, the error log including at least a first error code associated with the error condition; and
wirelessly send the error log to a remote device via the wireless controller.
2. The system of claim 1 , further including:
a self-check pin in operable communication with the microprocessor to detect a microprocessor failure condition;
wherein the microprocessor is to receive a signal indicative of a ground fault error from the ground fault detection unit; and
wherein the microprocessor is to store, in the error log, a first error code in response to detecting a ground fault error condition; a second error code in response to detecting a microprocessor failure condition; and a third error code in response to detecting a current mismatch condition, and wherein the error log is to associate an error code with an active time of the electric grill, a target temperature, the estimated ambient temperature, and a measured temperature at the time of the error condition.
3. The system of claim 1 , wherein the microprocessor is connected to at least one of a relay or a triac driver for controlling the current delivered to the heating element.
4. The system of claim 3 , wherein at least one of the microprocessor or a band controller is to, in response to receipt of an “off” signal from the remote device, disable current from being delivered to the heating element.
5. The system of claim 1 , wherein the temperature sensing device, is implemented using a thermocouple.
6. The system of claim 5 , further including a display in electronic communication with the microprocessor, wherein the microprocessor is to cause display of the estimated ambient temperature on the display.
7. The system of claim 6 , wherein the microprocessor is to toggle between displaying the temperature in Celsius or Fahrenheit in response to a wireless signal from the remote device.
8. The system of claim 5 , wherein the microprocessor is to wirelessly transmit the estimated ambient temperature to the remote device.
9. The system of claim 5 , wherein the microprocessor to record operating parameters of the electric grill and to wirelessly transmit the operating parameters to the remote device.
10. The system of claim 9 , wherein the microprocessor is to transmit the operating parameters continuously.
11. The system of claim 9 , wherein the microprocessor is to transmit the operating parameters in response to an error.
12. The system of claim 9 , wherein the operating parameters include a temperature measurement.
13. The system of claim 9 , wherein the operating parameters include a timer indicative of the amount of time the heating element has been active.
14. The system of claim 1 , wherein the remote device is to display, on a display of the remote device, a message indicative of the type of error corresponding to the received error code.
15. The system of claim 14 , wherein the remote device is a cell phone.
16. The system of claim 14 , wherein the remote device is a tablet device.
17. The system of claim 1 , wherein the microprocessor is a chip having a self-check pin, and the wireless controller is to wirelessly send an error code to the remote device in response to a self-check signal indicating a microprocessor error.
18. A method for wirelessly monitoring a status of an electric grill, the method comprising:
selecting an operating mode for a heating element using a user input device, the heating element connected to a voltage line and a neutral line via a triac and a latch relay;
displaying, on a display device, the selected operating mode;
causing delivery of current associated with the selected operating mode to the heating element via the triac and the latch relay;
utilizing a temperature sensing device to measure a temperature at a first position inside a cook box of the electric grill, the temperature sensing device positioned on a first side of a plane defined by a grill grate, the heating element positioned on the first side of the plane defined by the grill grate;
using a microprocessor to estimate an ambient temperature at a second position within the cook box based on the temperature measured by the temperature sensing device, wherein the second position is located on a second side of the plane defined by the grill grate, the second side of the plane opposite the first side of the plane;
using a current transformer to measure a current difference between the voltage line and the neutral line;
generating an electric signal indicating the current difference and responding to said current difference by activating a trip controller connected to the latch relay;
measuring, using a Hall Effect sensor, an electrical current delivered to the heating element;
detecting a ground fault error condition using a ground fault detection unit connected to the voltage line and the neutral line;
responding to the ground fault error condition by generating a signal indicative of the ground fault error condition;
determining, by executing an instruction with a microprocessor, an expected electrical current associated with the selected operating mode, the expected electrical current being electrical current reading expected during normal operating conditions in the selected operating mode;
detecting, by executing an instruction with the microprocessor, a current mismatch condition by comparing the measured electrical current to the expected electrical current;
disabling the latch relay to disable the heating element in response to a measured electrical current that is higher or lower than the expected electrical current; in response to detecting an error condition, storing an error log in a memory, wherein the error log includes at least a first error code associated with the error condition; and
transmitting the error log, wirelessly, to a remote device.
19. The method of claim 18 , further including:
using the microprocessor to determine an active time of the electric grill; and
transmitting, wirelessly, the temperature and the active time to the remote device.
20. The method of claim 19 , further including using the remote device to display, at the remote device, a message indicative of the error received.
21. The method of claim 20 , further including:
using a self-check pin to monitor a microprocessor failure condition;
storing, in the error log, a first error code in response to detecting a ground fault error condition, a second error code in response to detecting a microprocessor failure condition, or a third error code in response to detecting a current mismatch condition; and
associating each stored error code with the active time of the electric grill, a target temperature, and a measured temperature at the time of the error condition.
22. The method of claim 21 , further including using the remote device to communicate the log over the internet.
23. The method of claim 19 , further including displaying, on a display at the electric grill, the estimated ambient temperature.
24. The method of claim 23 , further including using the remote device to wirelessly toggle the display between Celsius and Fahrenheit.
25. An electric grill, comprising:
a housing having one or more user inputs for selecting a high, medium, or low operating mode of a heating element, and a display device to display the selected operating mode, the heating element being connected to a triac and further connected to a voltage line and a neutral line;
a latch relay connected between the heating element and the voltage line, the latch relay being in communication with a trip controller;
a ground fault detection unit in communication with the trip controller and configured to activate the trip controller in response to an unbalanced current between the voltage line and the neutral line;
a temperature sensing device for measuring temperature at a first position within the housing, the temperature sensing device positioned on a first side of a plane defined by a cooking surface, the heating element positioned on the first side of the plane defined by a cooking surface;
a microprocessor connected to a triac driver, the triac driver being in communication with the triac, wherein the microprocessor is to activate the triac driver to deliver a current associated with the selected operating mode; and
a Hall Effect sensor configured to measure current passing through the triac, the current sensor to communicate a measured current to the microprocessor;
wherein the microprocessor is to:
access a memory to retrieve an expected current associated with the selected high, medium, or low operating mode of the heating element;
calculate an estimated ambient temperature at a second position within the housing based on the measured temperature at the first position, the second position located on a second side of the plane defined by the cooking surface, the second side of the plane opposite the first side of the plane;
compare the measured current with the expected current for the selected high, medium, or low operating mode;
disable the latch relay to prevent the flow of current to the heating element in response to a measured current that is higher or lower than the expected current;
alert a user, via the display, that the flow of current has been disabled; and
cause transmission of an error message to a remote device via a wireless controller.
26. The electric grill of claim 25 , further including the wireless controller.