# US 12,000,605 B2 · Method for controlling balanced frosting of outdoor units in multi-split air-conditioning system

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- Number: US 12,000,605 B2
- Document ID: US12000605B2
- Status: Granted
- Kind: B2
- Application number: 17/641,973
- Filed: 2020-09-04
- Published: 2022-09-29
- Granted: 2024-06-04
- Earliest claimed: 2019-09-17
- Assignees: Qingdao Haier Air-conditioning Electronic Co., Ltd; Haier Smart Home Co., Ltd.
- Applicants: Qingdao Haier Air-conditioning Electronic Co., Ltd; Haier Smart Home Co., Ltd.
- Inventors: Baitian Zhuo; Bin Shi; Shaojiang Cheng; Ruigang Zhang; Jun Wang
- Web page: https://patentgrep.com/patent/US12000605B2

## CPC

- F24F 11/42: of outdoor units
- F25B 47/02: Defrosting cycles
- F24F 11/62: characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
- F24F 11/64: using pre-stored data
- F25B 13/00: Compression machines, plants or systems, with reversible cycle (defrosting cycles F25B47/02)
- F24F: AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING (removing dirt or fumes from areas where they are produced B08B15/00; vertical ducts for carrying away waste gases from buildings E04F17/02; tops for chimneys or ventilating shafts, terminals for flues F23L17/02)
- F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS

## Abstract

A method for controlling the balanced frosting of outdoor units in a multi-split air-conditioning system solving the problem in existing multi-split air-conditioning systems of resource waste caused by a low utilization efficiency of the heating capability of outdoor units as a result of some of the outdoor units entering a defrosting state when the heating capability is not fully utilized. According to the control method, by determining whether an outdoor unit set satisfies a frosting unbalance condition, the actual output capability of outdoor units of the outdoor unit set is selectively controlled on the basis of the frosting degrees of all the outdoor units. Thus, the difference between the frosting degrees of different outdoor units in the outdoor unit set at the same time can be reduced, such that the heating capability of all the outdoor units can be fully utilized when the outdoor unit set enters a defrosting state.

## Claims

### Claim 1

A method for controlling balanced frosting of outdoor units in a multi-connection air conditioning system, the method comprising:
calculating frosting degrees of all outdoor units in an outdoor unit set;
judging whether the outdoor unit set satisfies a frosting imbalance condition based on the frosting degrees of all the outdoor units and a preset frosting imbalance threshold; and
when the outdoor unit set satisfies the frosting imbalance condition, selectively controlling actual output capacities of the outdoor units in the outdoor unit set based on the frosting degrees of all the outdoor units, and making a total amount of the actual output capacities of all the outdoor units not less than a required total amount of the output capacity of the outdoor unit set.

### Claim 2 (depends on 1)

The control method according to claim 1, wherein the step of judging whether the outdoor unit set satisfies the frosting imbalance condition based on the frosting degrees of all the outdoor units and the preset frosting imbalance threshold comprises:
selecting a preset frosting degree reference value as the frosting imbalance threshold when only some of the outdoor units are turned on;
comparing the frosting degrees of all the outdoor units in the turned-on state with the preset frosting degree reference value respectively; and
if there is any one of all the outdoor units in the turned-on state whose frosting degree is greater than or equal to the preset frosting degree reference value, then determining that the outdoor unit set satisfies the frosting imbalance condition.

### Claim 3 (depends on 2)

The control method according to claim 2, wherein the controlling the actual output capacities of the outdoor units in the outdoor unit set based on the frosting degrees of all the outdoor units comprises:
selecting a maximum value of the frosting degrees of all the outdoor units in the turned-on state and a minimum value of the frosting degrees of all the outdoor units in a turned-off state and comparing the maximum value with the minimum value; and
controlling the actual output capacities of the outdoor units in the outdoor unit set based on a comparison result.

### Claim 4 (depends on 3)

The control method according to claim 3, wherein the controlling the actual output capacities of the outdoor units in the outdoor unit set based on the comparison result comprises:
if the minimum value of the frosting degrees is smaller than the maximum value of the frosting degrees, then turning off the outdoor unit corresponding to the maximum value of the frosting degrees, and turning on the outdoor unit corresponding to the minimum value of the frosting degrees.

### Claim 5 (depends on 4)

The control method according to claim 4, further comprising:
repeating the steps of:
selecting a maximum value of the frosting degrees of all the outdoor units in the turned-on state and a minimum value of the frosting degrees of all the outdoor units in a turned-off state and comparing the maximum value with the minimum value;
controlling the actual output capacities of the outdoor units in the outdoor unit set based on a comparison result; and
if the minimum value of the frosting degrees is smaller than the maximum value of the frosting degrees, then turning off the outdoor unit corresponding to the maximum value of the frosting degrees, and turning on the outdoor unit corresponding to the minimum value of the frosting degrees;
until the frosting degrees of the outdoor units in the turned-on state are each less than the frosting degrees of the outdoor units in the turned-off state.

### Claim 6 (depends on 1)

The control method according to claim 1, wherein the step of judging whether the outdoor unit set satisfies the frosting imbalance condition based on the frosting degrees of all the outdoor units and the preset frosting imbalance threshold comprises:
in a case where all the outdoor units in the outdoor unit set are turned on, using a preset standard difference of the frosting degree as the frosting imbalance threshold;
calculating a difference between a maximum value of the frosting degrees and a minimum value of the frosting degrees in all the current outdoor units;
comparing the difference with the standard difference of the frosting degree; and
if the difference is larger than or equal to the standard difference of the frosting degree, then determining that the outdoor unit set satisfies the frosting imbalance condition.

### Claim 7 (depends on 6)

The control method according to claim 6, wherein the controlling the actual output capacities of the outdoor units in the outdoor unit set based on the frosting degrees of all the outdoor units comprises:
calculating an average value of the frosting degrees of all the outdoor units;
using the average value of the frosting degree as a current frosting degree reference value; or using a sum of the average value of the frosting degrees and a set deviation value as the current frosting degree reference value; and
controlling the actual output capacities of the outdoor units in the outdoor unit set based on the frosting degrees of all the outdoor units and the current frosting degree reference value.

### Claim 8 (depends on 7)

The control method according to claim 7, wherein the controlling the actual output capacities of the outdoor units in the outdoor unit set based on the frosting degrees of all the outdoor units and the current frosting degree reference value comprises:
reducing the output capacities of the outdoor units whose frosting degrees are greater than the current frosting degree reference value, and/or increasing the output capacities of the outdoor units whose frosting degrees are less than the current frosting degree reference value.

### Claim 9 (depends on 1)

The control method according to claim 1, wherein the calculating the frosting degrees of all the outdoor units in the outdoor unit set comprises:
making a statistic on an actual duration in which a temperature of a condenser of the outdoor unit is lower than a preset temperature threshold; and
calculating a ratio of the actual duration to a preset duration as the frosting degree of the outdoor unit.

### Claim 10 (depends on 1)

The control method according to claim 1, further comprising:
controlling all the outdoor units in the outdoor unit set to enter a defrosting state, if there is any outdoor unit in the outdoor unit set whose frosting degree reaches a defrosting condition.