Conveying Temperature Information in a Controlled Variable Speed Heating, Ventilation, and Air Conditioning (HVAC) System

Abstract

The present invention provides methods and apparatuses that support the transfer of data from a thermostat unit to a controller unit to control a variable speed heating, ventilation, and air conditioning (HVAC) system. The duty cycle of a signal (that is sent from a thermostat unit to a controller unit) is adjusted in accordance with a temperature difference between the ambient temperature of an environmentally controlled space and a set temperature. The controller unit measures the duty cycle to determine the temperature difference and adjusts the speed of a blower motor or compressor in accordance with the temperature difference. The signal is switched on and off, in which the AC waveform is conducted and blocked by the thermostat unit and received by the controller unit. The controller unit measures the duty cycle of the received signal, determines the temperature from the duty cycle, and adjusts the speed from a predetermined relationship.

1 . A system for controlling an air conditioning unit, the air conditioning unit including a variable speed compressor, the system comprising:
 a thermostat unit including:
 a temperature sensor measuring an ambient temperature of an environmentally controlled space; 
 a switching module controlling conduction of a signal over a controlled time interval; and 
 a thermostat processing module determining a temperature difference between the ambient temperature and a set temperature, determines a duty cycle corresponding to the temperature difference, and controlling the switching module in accordance with the duty cycle, the signal being electrically conducted during an activated time duration and electrically blocked during an deactivated time duration over a time period, the duty cycle specifying the activated time duration and the deactivated time duration; and 
   a compressor controller unit including:
 a signal interface module monitoring the signal from the thermostat unit; and 
 a compressor controller processing module determining the duty cycle from the signal, determining the temperature difference from the duty cycle, and determining an updated compressor speed from the temperature difference, and instructing the variable speed compressor to function at the updated compressor speed. 
   
     
     
         2 . The system of  claim 1 , the switching module including an electrical component that electrically closes during the activated time duration and electrically opens during the deactivated time duration. 
     
     
         3 . The system of  claim 1 , the thermostat processing module processing the temperature difference between a range between T max  and −T max . 
     
     
         4 . The system of  claim 3 , thermostat processing module determining the duty cycle from the temperature difference divided by said T max  times 50% plus 50%. 
     
     
         5 . The system of  claim 4 , the thermostat processing module setting the temperature difference to a positive limited value when the temperature difference is greater than approximately T max  and setting the temperature difference to a negative limited value when the temperature is less than approximately −T max . 
     
     
         6 . The system of  claim 3 , the thermostat processing module sending a pulse having a pulse duration less than a minimum value when decoding the duty cycle as zero, the pulse being conveyed by the signal. 
     
     
         7 . The system of  claim 6 , the compressor controller processing module decoding the signal corresponding to the duty cycle as being zero when the pulse duration is less than the minimum value. 
     
     
         8 . The system of  claim 3 , the thermostat processing module sending a predetermined pulse pattern that designates an emergency stop, the predetermined pulse pattern being conveyed on the signal. 
     
     
         9 . The system of  claim 8 , the compressor controller processing module decoding the signal corresponding to the emergency stop and instructing the variable speed compressor to stop rotating. 
     
     
         10 . The system of  claim 1 , the switching module controlling the signal having a switched alternating current (AC) waveform. 
     
     
         11 . The system of  claim 1 , the compressor controller processing module determining the time period as a time value between raising edges of consecutive time durations. 
     
     
         12 . The system of  claim 1 , the thermostat unit sending configuration information to the compressor controller unit. 
     
     
         13 . The system of  claim 12 , the thermostat unit encoding a value of T max  in the configuration information. 
     
     
         14 . The system of  claim 1 , the compressor controller unit further including:
 a data structure that maps the temperature difference to the updated compressor speed; and   the compressor controller processing module access the data structure to determine an updated compressor speed.   
     
     
         15 . A thermostat unit for controlling an air conditioning unit, the air conditioning unit including a variable speed compressor, the thermostat unit comprising:
 a temperature sensor measuring an ambient temperature of an environmentally controlled space;   a switching module controlling conduction of a signal over a controlled time interval, the signal having a switched alternating current (AC) waveform; and   a thermostat processing module determining a temperature difference between the ambient temperature and a set temperature, determines a duty cycle corresponding to the temperature difference, and controlling the switching module in accordance with the duty cycle, the signal being electrically conducted during an activated time duration and electrically blocked during an deactivated time duration over a time period, the duty cycle specifying the activated time duration and the deactivated time duration.   
     
     
         16 . A thermostat unit of  claim 15 , the thermostat processing unit determining the duty cycle from the temperature difference divided by T max  times 50% plus 50%. 
     
     
         17 . A thermostat unit of  claim 15 , the switching module including an electrical component that electrically closes during the activated time duration and electrically opens during the deactivated time duration. 
     
     
         18 . A compressor controller unit for controlling an air conditioning unit, the air conditioning unit including a variable speed compressor, the compressor controller unit comprising:
 a signal interface module monitoring a signal from a thermostat unit, the signal having a switched alternating current (AC) waveform and being characterized by a duty cycle; and   a compressor controller processing module determining the duty cycle from the signal, determining the temperature difference from the duty cycle, and determining an updated compressor speed from the temperature difference, and instructing the variable speed compressor to function at the updated compressor speed.   
     
     
         19 . A compressor controller unit of  claim 18 , the compressor controller processing module decoding the signal by determining that the temperature difference equals the duty cycle minus 50% divided by 50% times T max . 
     
     
         20 . A compressor controller unit of  claim 18 , further comprising:
 a pulse width modulation controller controlling a pulse width of at least one control pulse in accordance with the temperature difference and a feedback signal from the variable speed compressor, the feedback signal being indicative of a difference between a target compressor speed and an actual compressor speed; and   an array providing at least one control signal to the variable speed compressor in accordance with the pulse width of the at least one control pulse from the pulse width modulation controller.   
     
     
         21 . A system for controlling a furnace, the furnace including a variable speed blower motor, the system comprising:
 a thermostat unit including:
 a temperature sensor measuring an ambient temperature of an environmentally controlled space; 
 a switching module controlling conduction of a signal over a controlled time interval; and 
 a thermostat processing module determining a temperature difference between the ambient temperature and a set temperature, determines a duty cycle corresponding to the temperature difference, and controlling the switching module in accordance with the duty cycle, the signal being electrically conducted during an activated time duration and electrically blocked during an deactivated time duration over a time period, the duty cycle specifying the activated time duration and the deactivated time duration; and 
   a furnace controller unit including:
 a signal interface module monitoring the signal from the thermostat unit; and 
 a furnace controller processing module determining the duty cycle from the signal, determining the temperature difference from the duty cycle, and determining an updated speed of the variable speed blower motor from the temperature difference, and instructing the variable speed blower motor to function at the updated compressor speed. 
   
     
     
         22 . The system of  claim 21 , the thermostat processing module processing the temperature difference between a range between T max  and −T max . 
     
     
         23 . The system of  claim 22 , the thermostat processing module determining the duty cycle from the temperature difference divided by said T max  times 50% plus 50%.