Flexible Use of an Inverter in a Refrigeration Unit

Abstract

A control system for a refrigeration unit being powered by a power source and having a compressor, an inverter and an evaporator fan is provided. The control system may include a first switch configured to selectively couple the compressor with one of the power source and the inverter, a second switch configured to selectively couple the evaporator fan with one of the power source and the inverter, and a controller operatively coupled to the first and second switches. The controller may be configured to engage the first and second switches into one of a first state and a second state based on a triggering event. In the first state, the first switch may be configured to couple the compressor with the power source and the second switch may be configured to couple the evaporator fan with the inverter. In the second state, the first switch may be configured to couple the compressor with the inverter and the second switch may be configured to couple the evaporator fan with the power source.

What is claimed is: 
     
         1 . A control system for a refrigeration unit being powered by a power source and having a compressor, an inverter and an evaporator fan, the control system comprising:
 a first switch configured to selectively couple the compressor with one of the power source and the inverter;   a second switch configured to selectively couple the evaporator fan with one of the power source and the inverter; and   a controller operatively coupled to the first and second switches and configured to engage the first and second switches into one of a first state and a second state based on a triggering event, the first switch being configured to couple the compressor with the power source and the second switch being configured to couple the evaporator fan with the inverter in the first state, the first switch being configured to couple the compressor with the inverter and the second switch being configured to couple the evaporator fan with the power source in the second state.   
     
     
         2 . The control system of  claim 1 , wherein the first state corresponds to full load operation of the refrigeration unit and the second state corresponds to part load operation of the refrigeration unit. 
     
     
         3 . The control system of  claim 1 , wherein the triggering event corresponds to a change in load demand of the refrigeration unit, the controller being configured to engage the first and second switches into the first state during full load operation and into the second state during part load operation. 
     
     
         4 . The control system of  claim 1 , wherein the triggering event corresponds to a change in temperature distribution within a cabinet of the refrigeration unit. 
     
     
         5 . The control system of  claim 1 , wherein the controller is configured to engage the first and second switches into the second state in response to any uneven temperature distribution detected within the cabinet. 
     
     
         6 . The control system of  claim 1 , wherein the controller is configured to engage the first and second switches into the first state in response to even temperature distribution within the cabinet. 
     
     
         7 . The control system of  claim 1 , wherein the compressor has a relatively higher load capacity than that of the inverter. 
     
     
         8 . The control system of  claim 7 , wherein the load capacity of the compressor is greater than that of the inverter by at least 1.5 times. 
     
     
         9 . A control system for a refrigeration unit being powered by a power source and having a compressor and an evaporator fan, the control system comprising:
 an inverter in communication with the power source;   one or more switches configured to selectively supply power from one of the power source and the inverter to the compressor and the evaporator fan; and   a controller operatively coupled to the switches and configured to engage the switches into one of a first state and a second state based on a triggering event, the controller engaging the switches to couple the power source with the compressor and the inverter with the evaporator fan in the first state, the controller engaging the switches to couple the inverter with the compressor and the power source with the evaporator fan in the second state.   
     
     
         10 . The control system of  claim 9 , wherein the first state corresponds to full load operation of the refrigeration unit and the second state corresponds to part load operation of the refrigeration unit. 
     
     
         11 . The control system of  claim 9 , wherein the triggering event corresponds to a change in load demand of the refrigeration unit, the controller being configured to engage the switches into the first state during full load operation and into the second state during part load operation. 
     
     
         12 . The control system of  claim 9 , wherein the triggering event corresponds to a change in temperature distribution within a cabinet of the refrigeration unit. 
     
     
         13 . The control system of  claim 9 , wherein the controller is configured to engage the switches into the second state in response to any uneven temperature distribution detected within the cabinet. 
     
     
         14 . The control system of  claim 9 , wherein the controller is configured to engage the first and second switches into the first state in response to even temperature distribution within the cabinet. 
     
     
         15 . The control system of  claim 9 , wherein a load capacity of the inverter is substantially less than that of the compressor. 
     
     
         16 . The control system of  claim 9 , wherein the switches include at least a first switch corresponding to the compressor and a second switch corresponding to the evaporator fan, the controller being configured to engage the switches between the first and second states simultaneously. 
     
     
         17 . The control system of  claim 9 , wherein the inverter is configured to supply pulsed power to one of the compressor and the evaporator fan. 
     
     
         18 . A method for controlling a refrigeration unit being powered by a main power source and having a compressor, an inverter and an evaporator fan, comprising the steps of:
 determining a load demand of the refrigeration unit;   generating a triggering event in response to a substantial change in the load demand; and   simultaneously interchanging the power supplied to each of the compressor and the evaporator fan in response to the triggering event.   
     
     
         19 . The method of  claim 18 , wherein the triggering event is generated when the load demand of the refrigeration unit changes from full to part load or from part to full load. 
     
     
         20 . The method of  claim 18 , wherein the compressor is powered by the main power source and the evaporator fan is powered by the inverter during full load operation, and the compressor is powered by the inverter and the evaporator fan is powered by the main power source during part load operation.