Abstract: A relay device and a multi-split control system that achieve reliable communication between an outdoor air conditioning unit and multiple indoor units under the condition that the length of a communication bus is limited. The system expands the communication distance by a cascade path formed by a plurality of relay devices. The cascade path transmits control signals sent by a master control device/a specific slave control device (i.e. a slave control device communicating with the master control device or certain relay device) to corresponding slave control devices one by one, and the corresponding slave control devices transmit the signals to the master control device/specific slave control device according to a response signal fed back by the control signal, where the relay devices may respectively communicate with a source node device and a destination node device on the basis of the master-slave type communication mode.

Abstract: An address competition method of a multi-connected type control system. The method aims at solving the problem of how to set an indoor machine communication address in the multi-connected type air conditioner system efficiently. For the purpose, a primary control device (such as an air conditioner outdoor machine) performs broadcasting on each address in a preset address section in sequence. A slave control device (such as the air conditioner indoor machine) responds to the primary control device on the basis of preset responding time and the number of currently broadcasting times of the primary control device. The primary control device to which a communication address is distributed temporarily is responded so as to finish address competition rapidly. Meanwhile, the primary control device can perform continuous broadcasting on one address for repeatedly, so that the competition success rate of the address is increased.

Abstract: An address competition method of a multi-connection type control system, intended to solve the problem of how to increase the efficiency of indoor air-conditioner unit address configuration where, according to the order in which a first slave control device initiates an address request, a relay device allocates, in sequence, temporary addresses to all first slave control devices, and according to the temporary addresses, initiates address requests in sequence to a master control device; according to the order in which a second slave control device initiates an address request, the master control device allocates, in sequence, official addresses to all second slave control devices; according to the temporary addresses, the relay device allocates the official addresses to the corresponding first slave control devices. The method can efficiently allocate an address to an indoor air-conditioner unit, and ensures that the address of each indoor air-conditioner unit is unique.

Abstract: An oil return control method for a multi-split air conditioner and a system accomplishing the same includes: calculating an average exhaust pressure within an oil return period Pd_AVG; determining whether the average exhaust pressure Pd_AVG?the set threshold Pdthreshold; if Pd_AVG?Pdthreshold, maintaining the multi-split air conditioner working in heating mode to ensure an acceptable oil return performance without affecting the air conditioning effect of indoor unit in heating mode; if Pd_AVG<Pdthreshold, switching the multi-split air conditioner to cooling mode, stopping a fan within those power-on indoor units and entering into a cooling oil return process and switching the multi-split air conditioner back to heating mode until the cooling oil return process ends.

Abstract: A comfort degree balance control system and method for multi-split air conditioner disclosed the present invention includes: obtaining a real-time ambient temperature and a target ambient temperature of each of rooms where an indoor unit provided is working; calculating a comfort degree deviation of each of the working indoor units; obtaining the maximum value offsetMAX and the minimum value offsetMIN among the comfort degree deviations of indoor units and calculating the difference A=offsetMAX?offsetMIN between the two; calculating an average comfort degree deviation; adjusting the amount of refrigerant flowing into working indoor units according to the difference A and the average comfort degree deviation, so as to reduce the difference A and balance the performance of the multi-split system.

Abstract: A defrosting control method for a multi-split system is provided. A multi-split system comprises an outdoor unit and multiple indoor units. An expansion valve is provided on a connecting pipeline between each of the indoor units and the outdoor unit. When the expansion valve of each activated indoor unit is closed and the degree of opening of the expansion valve of each off-state indoor unit is less than or equal to a maximum set degree of opening, the system satisfies a defrosting requirement, and as a result the method controls the expansion valve of each activated indoor unit to remain closed, thereby resolving the issue of a dramatic temperature drop in a room having an activated indoor unit during defrosting and improving user satisfaction. The degree of opening of the expansion valve of a off-state indoor unit is Off_PLS, and is controlled such that Off_PLS=ALL_HP*Avg_PLS/Off_HP.

Abstract: The present disclosure discloses a method and a device for controlling an expansion valve. The method includes: when a first specified number of indoor units are in a non-working state, turning off expansion valves corresponding to all the indoor units in the non-working state; and turning on expansion valves corresponding to a second specified number of indoor units in the non-working state in turn according to a predetermined cycle.

Abstract: The present disclosure disclosures a method and an apparatus for controlling a device. The method is applied in an indoor unit of a multi-split system and includes: when a temperature sensor fails, selecting other indoor units operating in the same operation mode with a current indoor unit from all indoor units; obtaining corresponding sensor parameters from temperature sensors of the indoor units operating in the same operation mode; and controlling the device according to the obtained sensor parameters.