Method for controlling constant air volume of ECM motor in HVAC system

Patent metadata

Field	Value
Publication number	US-9835350-B2
Application number	US-201614987694-A
Country	US
Kind code	B2
Filing date	Jan 4, 2016
Priority date	Jan 14, 2014
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

A method for controlling constant air volume of an ECM motor in an HVAC system. The method includes: a) acquiring a target air volume Q set input from an external, determining a function I tad =f(n) corresponding to the target air volume Q set by the microprocessor, in which I tad represents a bus current, n represents a rotational speed of the motor; b) acquiring a calculated bus current I tad according to the rotational speed n and the function I tad =f(n), and detecting a real-time bus current I bus ; and c) comparing the calculated bus current I tad with the real-time bus current I bus by the microprocessor for closed-loop control; when I tad >I bus , increasing the rotational speed n of the motor; when I tad <I bus , decreasing the rotational speed n of the motor; and when I tad =I bus , stopping regulating the rotational speed n and returning to B) for continuing the control of the constant air volume.

First claim

The invention claimed is:

1. A method for controlling constant air volume of an electronically commutated motor in an heating, ventilating, and air conditioning system,
the electronically commutated motor comprising: a stator assembly, a rotor assembly, and a motor controller; the motor controller comprising: a power circuit, a microprocessor, an inverter circuit, a rotor position detection circuit, and a bus current detection circuit; the electronically commutated motor driving the wind wheel; the power circuit supplying power to other circuits; the rotor position detection circuit detecting a rotor position signal and inputting the rotor position signal to the microprocessor; the microprocessor calculating a real-time rotational speed n according to the rotor position signal; the bus current detection circuit inputting a bus current to the microprocessor; the microprocessor controlling the inverter circuit; and the inverter circuit controlling an energization state of each coil winding of the stator assembly;
the method comprising:
a) acquiring a target air volume Q set input from an external, determining a function I tad =f(n) corresponding to the input target air volume Q set by the microprocessor, in which, I tad represents a bus current, n represents a rotational speed of the motor, n min <n<n max , n min represents a minimum critical rotational speed of the function I tad =f(n) corresponding to the input target air volume, n max represents a maximum critical rotational speed of the function I tad =f(n) corresponding to the input target air volume; when the motor is in a halt state, operating the motor and acquiring an original rotational speed n of the motor by the microprocessor; and when the motor is in an operating state, acquiring a current rotational speed n of the motor by the microprocessor;
b) acquiring a calculated bus current I tad according to the rotational speed n of the motor and the function I tad =f(n), and detecting a real-time bus current I bus ; and
c) comparing the calculated bus current I tad with the real-time bus current I bus by the microprocessor for closed-loop control; when the calculated bus current I tad is larger than the real-time bus current I bus , increasing the rotational speed n of the motor; when the calculated bus current I tad is smaller than the real-time bus current I bus , decreasing the rotational speed n of the motor; and when the calculated bus current I tad is equal to the real-time bus current I bus , stopping regulating the rotational speed n of the motor and allowing the electronically commutated motor to enter a working condition, and returning to B) for continuing the control of the constant air volume.

2. The method of claim 1 , further comprising determining whether the rotational speed is within the range of between n min and n max before regulating the rotational speed of the motor in c), and employing a critical rotational speed as a next rotational speed and repeating b) and c) when the rotational speed is out of the range of between n min and n max .

3. The method of claim 1 , wherein “when the calculated bus current I tad is equal to the real-time bus current I bus ” means that an error of the real-time bus current I bus deviated from the calculated bus current I tad is within a certain range.

4. The method of claim 2 , wherein “when the calculated bus current I tad is equal to the real-time bus current I bus ” means that an error of the real-time bus current I bus deviated from the calculated bus current I tad is within a certain range.

5. The method of claim 1 , wherein the function I tad =f(n) is acquired as follows: for each target air volume, gradually increasing a static pressure within a range covering an actual static pressure range while allowing the motor to be in a constant rotational speed control; regulating a rotational speed of a back pressure fan in an air duct or an opening of an air door for ensuring the real-time air volume equal to the target air volume, and recording the rotational speed n of the motor in a stable state and the DC bus current I tad so that a group of the rotational speed n and the DC bus current I tad are obtained corresponding to each target air volume; and acquiring the function I tad =f(n) corresponding to each target air volume by curve fitting.

6. The method of claim 2 , wherein the function I tad =f(n) is acquired as follows: for each target air volume, gradually increasing a static pressure within a range covering an actual static pressure range while allowing the motor to be in a constant rotational speed control; regulating a rotational speed of a back pressure fan in an air duct or an opening of an air door for ensuring the real-time air volume equal to the target air volume, and recording the rotational speed n of the motor in a stable state and the DC bus current I tad so that a group of the rotational speed n and the DC bus current I tad are obtained corresponding to each target air volume; and acquiring the function I tad =f(n) corresponding to each target air volume by curve fitting.

7. The method of claim 1 , wherein
the function I tad =f(n) is a polynomial function: I tad =C 1 +C 2 ×n+ . . . +C m ×n m-1 , in which C 1 , C 2 , . . . , and C m represent coefficients, n represents the rotational speed of the motor; each target air volume corresponds to one group of coefficients C 1 , C 2 , . . . , and C m and the corresponding coefficients are stored; and
one group of coefficients C 1 , C 2 , . . . , and C m are acquired by the microprocessor by a look-up table method according to the input target air volume Q set , whereby acquiring the function I tad =f(n).

8. The method of claim 2 , wherein
the function I tad =f(n) is a polynomial function: I tad =C 1 +C 2 ×n+ . . . +C m ×n m-1 , in which C 1 , C 2 , . . . , and C m represent coefficients, n represents the rotational speed of the motor; each target air volume corresponds to one group of coefficients C 1 , C 2 , . . . , and C m and the corresponding coefficients are stored; and
one group of coefficients C 1 , C 2 , . . . , and C m are acquired by the microprocessor by a look-up table method according to the input target air volume Q set , whereby acquiring the function I tad =f(n).

9. The method of claim 1 , wherein
in acquiring the target air volume Q set input from the external in a), when the motor is in the halt state, the original rotational speed n of the motor is an intermediate value in a normal rotational speed range of the motor.

10. The method of claim 2 , wherein
in acquiring the target air volume Q set input from the external in a), when the motor is in the halt state, the original rotational speed n of the motor is an intermediate value in a normal rotational speed range of the motor.

11. The method of claim 1 , wherein
each target air volume Q set input from the external corresponds to a certain range of a duty ratio of a PWM signal input from the external, a relay signal, a digital communication signal, or a signal similar to a 0-10 VAC analog signal.

12. The method of claim 2 , wherein
each target air volume Q set input from the external corresponds to a certain range of a duty ratio of a PWM signal input from the external, a relay signal, a digital communication signal, or a signal similar to a 0-10 VAC analog signal.

13. The method of claim 1 , wherein
increasing or decreasing the rotational speed n of the motor is realized by increasing or decreasing a duty ratio of a PWM signal input into the inverter circuit by the microprocessor.

14. The method of claim 2 , wherein
increasing or decreasing the rotational s

Assignees

• Zhongshan Broad Ocean Motor Co

Inventors

• Hu Ge

Classifications

• F24F11/62

  characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values · CPC title

• F24F11/30 Primary

  for purposes related to the operation of the system, e.g. for safety or monitoring · CPC title

• F24F3/048

  with temperature control at constant rate of air-flow · CPC title

• G05B15/02

  electric · CPC title

• F24F11/75 Primary

  for maintaining constant air flow rate or air velocity · CPC title