Fan control system with charging controller for gas fireplace

Abstract

A Direct Current (D.C.) fan motor control system for an air cooled thermoelectric power generator. This electronic control system addresses the unique challenges that exist when thermoelectric generator (TEG) modules are used in a gas fireplace appliance to use D.C. fans as the primary air circulation element. Ideally, it is necessary to generate sufficient voltage for a fan motor while maximizing the efficiency of the overall system to permit the surplus energy generated above that required for the fan motor to be used to charge batteries, including a cellular phone handset battery. DC to DC switching converter techniques are used to manage the surplus energy available. A microcontroller based supervisor will monitor the TEG output voltage and determine when an electromechanical latching relay supplying power to the fan motor should be switched to the output of the DC to DC step down (buck) converter for maximum efficiency. The microcontroller also supervises a DC to DC step down converter assigned to charging a cellular phone by disabling the cellular handset charging function when the TEG output voltage is insufficient to maintain the fan and the cellular handset charger, thus prioritizing the fan motor function as the highest priority for the best reliability.

Claims

1. A system and method for managing and controlling a Direct Current (D.C.) fan motor providing cold side air convection with thermoelectric generator (TEG) arrays for hearth devices providing a combustion site, comprising: a) a printed circuit board with a microcontroller to direct the sequence and operation of the circuit elements contained therein; b) an electromechanical latching relay, responsive to operation by said microcontroller coupled to at least one D.C. fan motor; c) at least one wireless communications means for SMS text message control, responsive to said microcontroller; d) at least one electromechanical ignition relay means responsive to operation by said microcontroller; e) at least one charging means to connect to any compatible cellular phone handset with a suitable charging port; f) at least one standard Wi-Fi switching router apparatus; g) at least one battery charging means to support the connection and charging of any compatible battery of any electrochemical construction; h) a plurality of electronic DC to DC step down switching converters with at least one DC to DC converter for each fan motor, at least one DC to DC converter for the cellular handset charging port, and at least one DC to DC converter for external battery charging;

2. A system and method as defined in claim 1 wherein said fan motor receives an electrical energizing voltage through a first contact of said electromechanical latching relay, responsive to a first signal from said microcontroller which monitors the output voltage from the thermoelectric generator (TEG), using an integral Analog to Digital conversion means as part of said microcontroller, causing the fan motor to receive the energizing voltage directly from the TEG when the output voltage is less than the rated voltage of said fan motor, further causing the fan motor to receive the energizing voltage from the output of a DC to DC step-down switching converter through a second contact of said electromechanical latching relay in response to a second signal from said microcontroller when the output voltage from the TEG is at or above the rated voltage for the fan motor, thereby allowing said fan motor to operate at the rated voltage specified by the manufacturer of said fan motor, through said DC to DC step-down switching converter, establishing the appropriate conditions for an energy surplus to be achieved in proportion to the potential difference between the maximum TEG 10 voltage and the rated voltage of the fan motor.

3. A system and method as defined in clam 1 wherein said communication means for a preferred embodiment of this controller is implemented using the Global System for Mobile (GSM) communications protocol standard compatible with cellular telephone handset devices, responsive to control and operation signals from said microcontroller, capable of monitoring voltage and temperature conditions and reporting the data by means of Short Message Service (SMS) text message transmissions to and from the cellular handset means.

4. A system and method as defined in clam 1 wherein said communication means is implemented using the Code Division Multiple Access (CDMA) communications protocol standard compatible with cellular telephone handset devices, responsive to control and operation signals from said microcontroller, capable of monitoring voltage and temperature conditions and reporting the data by means of Short Message Service (SMS) text message transmissions to and from the cellular handset means.

5. A system and method as defined in clam 1 wherein the cellular charging means is implemented using a DC to DC step-down switching converter means with at least a fixed 5 Volt D.C. output, capable of facilitating a connection means using a suitable cable for charging the cellular handset, responsive to a signal from said microcontroller monitoring the TEG output voltage to enable or disable the 5 Volt charging potential energy output, said microcontroller using an integral Analog to Digital conversion means to measure the TEG output voltage to determine the threshold voltage at which said microcontroller enables or disables the charging means.

6. A system and method as defined in clam 5 wherein the cellular charging means is implemented using a DC to DC step-down switching converter means with at least a fixed 5 Volt D.C. output, with at least one battery of any electrochemical construction to absorb short term variations in the output of the 5V D.C. output while charging said battery.

7. A system and method as defined in clam 5 wherein the cellular charging means is implemented using a DC to DC step-down switching converter means with at least a fixed 5 Volt D.C. output, with at least one battery of any electrochemical construction to absorb short term variations in the output of the 5V D.C. output while charging said battery, and including a double layer super capacitor array whereby said super capacitor array is used to allow said battery to be connected by an isolation means such that said battery is isolated from the charging circuit, thereby allowing said battery to be charged while it is isolated from said super capacitor array, responsive to a signal from said microcontroller which controls the period and duration of the isolation means.

8. A system and method as defined in clam 1 wherein the battery charging means is implemented using a DC to DC step-down switching converter with a at least a fixed 13.8 Volt D.C. output, capable of charging at least a 12 Volt battery.

9. A system and method as defined in clam 1 wherein said ignition relay means is responsive to a signal from said microcontroller, which is further responsive through firmware to an SMS text message through said communication means requesting that said ignition relay contacts should be closed for a minimum time duration deemed sufficient to cause the gas to be ignited.

10. A system and method as defined in clam 1 wherein said communications means is optionally implemented as a wireless network communications node, specifically referred to as an Internet Of Things (IOT) node, responsive to a signal from said microcontroller, which is further responsive through firmware in receipt of a message from another node within range through said communication means requesting that said ignition relay contacts should be closed for a minimum time duration deemed sufficient to cause the gas to be ignited.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0010] An illustrative embodiment of the present invention is described by way of example only, with reference to the appended drawing figures, wherein:

[0011] FIG. 1 is a diagram of one embodiment of a fan motor control system of the present invention;

DETAILED DESCRIPTION

[0012] It should be understood that the present invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of includes, including, comprising, or having and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms connected, coupled, configured and mounted and variations thereof herein are used broadly and encompass direct and indirect connections, couplings and mountings. In addition, the terms connected and coupled and variations thereof are not restricted to physical, mechanical or electrical connections or couplings. Furthermore, and as described in subsequent paragraphs, the specific mechanical and/or other configurations illustrated in the drawings are intended to exemplify embodiments of the invention. However, other alternative mechanical and/or electrical and other configurations are possible which are considered to be within the teachings of the disclosure.

[0013] FIG. 1 shows one embodiment of a thermoelectric power generation control system in accordance with the teachings of the present invention. The electrical output of thermoelectric generator module array (TEG) 10 is coupled to the system controller apparatus to provide a voltage sufficient to cause fan motor 60 to operate at the maximum rated voltage for the fan motor when the output voltage of TEG 10 has reached a state of equilibrium whereby the maximum heat flux has been established. At startup when the gas has been ignited and the delta temperature is zero, the output voltage from the TEG 10 will be zero volts. As the temperature rises and the delta temperature increases, the Direct Current (D.C.) output voltage from the TEG 10 will increase in proportion to the delta temperature across the hot and cold sides of the TEG.

[0014] The output from the TEG 10 is connected to microcontroller 120 through a suitable conditioning and regulation device of 3.3 Volts D.C., to provide power to the microcontroller 120 and as the output voltage from the TEG 10 passes 3.3 Volts D.C., the microcontroller 120 begins operating and executing the user program. The microcontroller monitors the voltage from the TEG 10 with an integral Analog to Digital Converter inside the microcontroller 120 and when the output voltage from the TEG 10 reaches 5 Volts D.C., the stored microcontroller program pulses the SET coil of latching Relay 50 for 200 milliseconds. The connection circuit from the output of Relay 50 is connected to Fan Motor 60 in such a way that the voltage to the fan is routed from either of two sources through the relay. One such path is through the relay contacts joining the output from the TEG 10 directly to the motor. The second path is through the relay contacts joining the output of DC-DC converter 40 to the motor.

[0015] DC-DC converter 40 is a step-down switching regulator with a fixed output voltage of 12 Volts D.C., which is the rated voltage of Fan Motor 60. Switching DC-DC step down converters are considered to be very efficient due to the way they regulate the output voltage without consuming more energy from the source voltage than is required to maintain output regulation. Analog regulators by contrast are required to dissipate the voltage differential between input and output as excess heat thus a switching regulator is preferred. DC-DC converter 40 is responsive to a control signal from microcontroller 120 allowing the output voltage to be pulsed on and off periodically for 50 to 75 milliseconds every 333.3 milliseconds. This reduces the average current supplied to the fan while exploiting the kinetic energy stored in the rotating rotor assembly when the output from the TEG supports this operation.

[0016] Fan motor 60 will begin to operate at approximately 50% of the maximum rated voltage applied. For the particular fan used, the rated voltage is 12 Volts D.C., thus the fan will begin rotating when the TEG 10 reaches approximately 6 Volts D.C. and Relay 50 is configured to route the TEG 10 output voltage directly to the fan motor 60 to ensure that the motor receives an energizing voltage directly from the TEG 10 while the output voltage from the TEG 10 is below 12 Volts D.C., which is the maximum rated voltage of the fan motor. This will cause the fan motor to supply air flow as quickly as possible by following the rising output voltage from the TEG 10 as it is directly applied to the fan motor.

[0017] The Microcontroller 120 monitors the output voltage from the TEG 10 as it rises and when the output voltage reaches 12 Volts D.C., the fan motor has reached its rated voltage. The output voltage from the TEG 10 will continue to increase beyond 12V as the temperature increases proportionally, and the controller will supply energizing pulses to the fan motor at periodic intervals.

[0018] The quantity and arrangement of the TEG 10 devices is such that the output voltage from the TEG 10 array is predicted to be greater than the output of the maximum rated voltage of the fan motor. This ensures that additional surplus energy is available for battery charging or other purposes. Since the fan motor 60 rated voltage is 12 Volts D.C., there is provided a means to limit the fan motor voltage to a maximum of 12 Volts D.C. through DC-DC converter 40 which is a switching step-down regulator. Microcontroller 120 pulses the RESET coil of latching Relay 50 for 200 milliseconds, which reconfigures the interconnection of the TEG 10 output so that the Fan motor 60 receives its energizing voltage from DC-DC converter 40 at an output voltage of 12 Volts D.C., which fixes the fan motor voltage at 12 Volts D.C. with energizing pulses.

[0019] The output voltage of the TEG 10 array is typically higher than the fan motor rated voltage of 12 Volts D.C. This arrangement supports the generation of an energy surplus that can be directed to other circuit functions, including Battery Charging 90 through DC-DC converter 70 which is configured to float charge a 12 Volt D.C. battery at a fixed voltage of 13.8 Volts D.C.

[0020] Another battery charging function includes USB Charging 20 cell phone charging port through DC-DC converter 30 which is a fixed output voltage charging port at 5 Volts D.C. through a standard type A USB connector with a compatible cable to a cell phone. During utility power disruptions when AC line voltage is unavailable, there is provided a mean to charge a cell phone from this circuit, as well as the ability to charge a 12 Volt D.C. battery through Battery Charging port 90.

[0021] Microcontroller 120 monitors the output voltage of the TEG 10 array in order to ensure that enough surplus energy exists to maintain the fan motor voltage and charge a cell phone simultaneously. There may however be circumstances when that surplus energy drops below a threshold that is sufficient to maintain the air flow from the fans while charging a cell phone battery. If the gas flow is restricted for example to reduce the ambient temperature in the room where it is perceived to be too warm, then the output voltage will be reduced. Microcontroller 120 will disable the cell phone charging port during that time to maintain the fan motor voltage as a priority. When the voltage is again increased from the TEG 10 by increasing the gas flow creating a hotter combustion site, microcontroller 120 will enable the cell phone charging port. Without this feature, the current drawn by both the fan motor and the USB Charging 20 port at reduced temperatures would cause the fan motor to stall which will eventually result in thermal runaway as a result of undesired warming of the cold side surface of the TEG 10 resource.

[0022] There is provided a means to allow the system controller to be responsive to both GSM cellular communications, and industry standard Wi-Fi networking support with an Ethernet routing switcher as part of the managed resources of the controller. On-board microcontroller 120 firmware supports external monitoring functions by allowing a cellular phone handset with SMS text messaging to receive status messages regarding the condition of the environment such as the TEG 10 output voltage, temperature and any other parameter considered useful to monitor. GSM Input/output (I/O) 100 is a hardware resource configured to facilitate this function. Further, the user may choose to send an SMS text message to the GSM I/O 100 hardware to remotely activate Ignition Relay 80 thus causing the gas appliance to operate. The GSM I/O 100 hardware is configured to at least optionally transmit periodic temperature and voltage readings to the user cell phone thus confirming operation of the appliance if the user desires.

[0023] There is provided a means to allow the system controller to support Internet of Things (IOT) networking with a wireless hardware radio as part of the managed resources of the controller. On-board microcontroller 120 firmware is responsive to messages received by the IOT Input/output (I/O) 130 hardware node, to remotely activate Ignition Relay 80 thus causing the gas appliance to ignite the burner. The IOT I/O 130 hardware is responsive to a signal from microcontroller 120 to at least optionally transmit periodic temperature and voltage readings to another node in the network, thus confirming operation of the appliance if the user desires.

[0024] Wi-Fi switching router WI-FI Input/output (I/O) 110 is present to provide internet routing and switching functions in the event of a power disruption to continue to provide internet access. If the Internet Service Provider (ISP) is capable of maintaining Internet communications to the entry point of demarcation of the residence, then Battery Charger 90 can maintain the charge on the battery, which serves as the power supply to the Internet Modem device, thereby allowing the continuation of Internet communications in conjunction with WI-FI I/O 110 which also uses the power supplied by the TEG 10 resource, independent of the status of external line voltage conditions for convention AC distribution.

[0025] While the invention has been described with reference to specific embodiments, modifications and variations of the invention may be constructed without departing from the scope of the invention, which is defined in the following claims.