Method for controlling capacity and starting of parallel magnetic suspension water chilling unit

The invention discloses a method for controlling the capacity and starting of a parallel magnetic suspension water chilling unit. The problems that an existing parallel magnetic suspension water chilling unit is high in energy consumption during starting and running, and a stopped compressor is difficult to start are mainly solved. The control method is characterized by comprising the following steps: (1) starting the capacity of the parallel magnetic suspension water chilling unit, so that the cooling capacity supply and the tail end load heat are balanced; and (2) the working frequency of the compressors is adjusted under the condition that cooling capacity supply and tail end load heat are balanced, so that the frequency of each running compressor (1) is kept to run within the range of 30%-70%. Each magnetic suspension centrifugal compressor can be effectively controlled to run under medium and low loads (30%-70% of the full load), the energy consumption is low, the energy-saving effect is good, the system