Adaptive control for motor fan with multiple speed taps

1. A circulator blower controller for a circulator blower of a heating, ventilation, and air conditioning (HVAC) system of a building, the circulator blower controller comprising:

an interface configured to receive a demand signal from a thermostat, the demand signal specifying an operating mode for the HVAC system;

a switching circuit configured to, in response to a tap selection signal, selectively connect power to one of a plurality of taps of a motor of the circulator blower;

a data store configured to store a mapping from a plurality of speeds to the plurality of taps; and

a processor configured to:

for each tap of the plurality of taps, observe power consumed by the circulator blower while power is connected to the tap by the switching circuit;

determine the mapping by sorting the taps based on observed power consumption;

select a first speed based on the demand signal from the thermostat;

identify a first tap from the mapping based on the first speed; and

in response to identifying the first tap, generate the tap selection signal to control the switching circuit to connect power to the first tap.

2. A circulator blower system comprising:

the circulator blower controller of claim 1 ; and

the circulator blower, wherein the circulator blower includes (i) the motor and (ii) a fan driven by the motor and configured to circulate air within the building.

3. The circulator blower system of claim 2 , wherein the motor comprises at least one of:

an electronically commutated motor (ECM) configured such that each of the plurality of taps instructs the ECM to run at a respective speed; and

a permanent split capacitor (PSC) motor including a winding and configured such that each of the plurality of taps corresponds to different points along the winding.

4. The circulator blower system of claim 3 , wherein the motor comprises:

the ECM;

a plurality of sensors that determine which of the plurality of taps is activated; and

a speed controller configured to control the ECM to rotate at a speed based on which of the plurality of taps is activated.

5. The circulator blower controller of claim 1 , wherein the operating mode is selected from a plurality of operating modes that include a cool mode and a fan only mode.

6. The circulator blower controller of claim 5 , wherein the processor is configured to, in response to the demand signal specifying the fan only mode, set the first speed to a speed defined by a user of the building.

7. The circulator blower controller of claim 5 , wherein:

the plurality of operating modes further includes a heat mode; and

the processor is configured to, in response to the demand signal specifying the heat mode, set the first speed to a speed defined by a user of the building.

8. The circulator blower controller of claim 5 , wherein the processor is configured to, in response to the demand signal specifying the cool mode:

select the first speed according to a predetermined initial speed;

after a first predetermined period of time following selection of the first speed, select a second speed that is faster than the first speed; and

in response to selection of the second speed, (i) identify a second tap from the mapping based on the second speed and (ii) generate the tap selection signal to control the switching circuit to connect power to the second tap.

9. The circulator blower controller of claim 8 , wherein the predetermined initial speed is a lowest speed of the circulator blower.

10. The circulator blower controller of claim 8 , wherein the processor is configured to, in response to the demand signal specifying the cool mode:

after a second predetermined period of time following selection of the second speed, select a third speed that is faster than the second speed; and

in response to selection of the third speed, (i) identify a third tap from the mapping based on the third speed and (ii) generate the tap selection signal to control the switching circuit to connect power to the third tap.

11. The circulator blower controller of claim 5 , wherein the processor is configured to, in response to the demand signal specifying the cool mode:

select the first speed according to a predetermined initial speed;

evaluate an operating condition of the HVAC system;

in response to the operating condition of the HVAC system meeting a first predetermined criterion, select a second speed that is faster than the first speed; and

in response to selection of the second speed, identify a second tap from the mapping based on the second speed and generate the tap selection signal to control the switching circuit to connect power to the second tap.

12. The circulator blower controller of claim 11 , wherein:

the operating condition of the HVAC system is temperature split;

the temperature split is based on a difference between supply air leaving an evaporator coil of the HVAC system and return air arriving at the evaporator coil;

the processor is configured to integrate time periods during which the temperature split diverged from a predetermined temperature profile; and

the first predetermined criterion is the integration exceeding a first threshold.

13. The circulator blower controller of claim 12 , wherein the processor is configured to, in response to determining that a humidity in a conditioned space of the building exceeds a desired humidity, increase the first threshold.

14. The circulator blower controller of claim 12 , wherein the processor is configured to perform the integration by, for each time period during which the temperature split diverged from the predetermined temperature profile, adding a product of a gain factor and a length of the time period to an accumulator register.

15. The circulator blower controller of claim 12 , wherein the processor is configured to:

in response to selection of the second speed, (i) evaluate the operating condition of the HVAC system and (ii) in response to the operating condition of the HVAC system meeting a second predetermined criterion, select a third speed that is faster than the second speed; and

in response to selection of the third speed, (i) identify a third tap from the mapping based on the third speed and (ii) generate the tap selection signal to control the switching circuit to connect power to the third tap,

wherein the second predetermined criterion is the integration exceeding a second threshold.

16. The circulator blower controller of claim 11 , wherein the processor is configured to, after a first predetermined period of time following selection of the first speed, select the second speed.

17. The circulator blower controller of claim 16 , wherein the processor is configured to, in response to determining that a humidity in a conditioned space of the building exceeds a desired humidity, increase the first predetermined period of time.

18. The circulator blower controller of claim 5 , wherein the processor is configured to, in response to the demand signal specifying the cool mode:

selectively determine a refrigerant undercharge condition of the HVAC system; and

in response to determining the refrigerant undercharge condition, (i) select a slower speed, (ii) identify a second tap from the mapping based on the slower speed, and (iii) generate the tap selection signal to control the switching circuit to connect power to the second tap.

19. The circulator blower controller of claim 1 , wherein:

the processor is configured to, until the mapping includes entries for all of the plurality of taps, observe the power consumed; and

observing the power consumed includes, while no demand signal is received from the thermostat, iterating through taps of the plurality of taps by generating the tap selection signal to control the switching circuit to connect power to an evaluation tap and observing the power consumed while power is connected to the evaluation tap.

20. The circulator blower controller of claim 1 , wherein the processor is configured to generate the tap selection signal to control the switching circuit to connect power to a second tap in response to determining that the motor is not operating while power is connected to the first tapa.