An electronic control system of a variable capacity compressor, comprising an inverter that is configured to receive external control signals, and to generate signals to drive the compressor, wherein the inverter has: a power circuit for adjusting the feed voltage of the compressor, with a feed input for alternating current, a continuous voltage bus and a variable amplitude and frequency voltage output to feed the compressor, at least one internal processing circuit, and an auxiliary power supply configured to provide internal feed voltages to the inverter and activate its running, characterized in that the inverter also comprises a circuit breaker with a first input configured to receive from a communication unit of the inverter an external signal to activate the auxiliary power supply, a second input configured to receive from the at least one internal processing circuit of the inverter an internal maintenance signal to maintain the auxiliary power supply activated, a third input connected to the continuous voltage bus of the power circuit and an output connected to an input of the auxiliary power supply, and when the external signal to the first input to activate the auxiliary power supply indicates that the auxiliary power supply should be connected, the circuit breaker is configured to enable the running of the auxiliary power supply, which activates the running of the inverter, and the at least one internal processing circuit of the inverter is configured to begin sending, continually, the internal maintenance signal 1 to activate the auxiliary supply to the circuit breaker indicating that the auxiliary power supply should be kept connected, and making the circuit breaker keep the auxiliary power supply enabled, when the external signal to activate the auxiliary power supply indicates that the auxiliary power supply should be disconnected, and the at least one internal processing circuit of the inverter is configured to stop sending the internal maintenance signal to maintain the auxiliary power supply activated to the circuit breaker, the circuit breaker is configured to disable the auxiliary power supply, to deactivate the running of the inverter, the inverter further comprises the communication unit configured to have an input that is configured to receive the external control signals for connecting or disconnecting the auxiliary power supply from a thermostat external to the inverter and an additional feed connection with the power circuit that feeds and keeps the communication unit activated, when the auxiliary power supply is disconnected, and wherein the thermostat is also configured to send to the communication unit operation control signals of the compressor by way of the same physical means of connection used for sending the external control signals for connecting and disconnecting the auxiliary power supply. a power circuit for adjusting the feed voltage of the compressor, with a feed input for alternating current, a continuous voltage bus and a variable amplitude and frequency voltage output to feed the compressor, at least one internal processing circuit, and an auxiliary power supply configured to provide internal feed voltages to the inverter and activate its running, characterized in that the inverter also comprises a circuit breaker with a first input configured to receive from a communication unit of the inverter an external signal to activate the auxiliary power supply, a second input configured to receive from the at least one internal processing circuit of the inverter an internal maintenance signal to maintain the auxiliary power supply activated, a third input connected to the continuous voltage bus of the power circuit and an output connected to an input of the auxiliary power supply, and when the external signal to the first input to activate the auxiliary power supply indicates that the auxiliary power supply should be connected, the circuit breaker is configured to enable the running of the auxiliary power supply, which activates the running of the inverter, and the at least one internal processing circuit of the inverter is configured to begin sending, continually, the internal maintenance signal 1 to activate the auxiliary supply to the circuit breaker indicating that the auxiliary power supply should be kept connected, and making the circuit breaker keep the auxiliary power supply enabled, when the external signal to activate the auxiliary power supply indicates that the auxiliary power supply should be disconnected, and the at least one internal processing circuit of the inverter is configured to stop sending the internal maintenance signal to maintain the auxiliary power supply activated to the circuit breaker, the circuit breaker is configured to disable the auxiliary power supply, to deactivate the running of the inverter, the inverter further comprises the communication unit configured to have an input that is configured to receive the external control signals for connecting or disconnecting the auxiliary power supply from a thermostat external to the inverter and an additional feed connection with the power circuit that feeds and keeps the communication unit activated, when the auxiliary power supply is disconnected, and wherein the thermostat is also configured to send to the communication unit operation control signals of the compressor by way of the same physical means of connection used for sending the external control signals for connecting and disconnecting the auxiliary power supply.