A drive includes an inverter power circuit that applies power to an electric motor of a compressor from a direct current (DC) voltage bus. A power factor correction (PFC) circuit outputs power to the DC voltage bus based on input alternating current (AC) power. The PFC circuit includes: (i) a switch having a first terminal, a second terminal, and a control terminal; (ii) a driver that switches the switch between open and closed states based on a control signal; (iii) an inductor that charges and discharges based on switching of the switch; and (iv) a circuit that outputs a signal indicating whether the switch is in the open state or the closed state based on a voltage across the first and second terminals of the switch.

A power conversion device includes a diode built-in transistor configured to include a transistor configured to be driven by a drive signal input into a gate, a diode configured to be connected in parallel with transistor, and have a forward direction from an emitter to a collector of the transistor, and sense diode configured to detect a current flowing in the diode, and have a cathode connected with the collector of the transistor; voltage generation part configured to generate, in a case where the diode does not conduct electricity, voltage between an anode of the diode and an anode of the sense diode, the voltage having a predetermined or greater difference with respect to a case where the diode conducts electricity; and determination part configured to determine whether the diode conducts electricity, based on the voltage between the anode of the diode and the anode of the sense diode.

A power conversion device includes a diode built-in transistor configured to include a transistor configured to be driven by a drive signal input into a gate, a diode configured to be connected in parallel with transistor, and have a forward direction from an emitter to a collector of the transistor, and sense diode configured to detect a current flowing in the diode, and have a cathode connected with the collector of the transistor; voltage generation part configured to generate, in a case where the diode does not conduct electricity, voltage between an anode of the diode and an anode of the sense diode, the voltage having a predetermined or greater difference with respect to a case where the diode conducts electricity; and determination part configured to determine whether the diode conducts electricity, based on the voltage between the anode of the diode and the anode of the sense diode.

A control device of a power switch includes a voltage boost circuit, a discharge circuit and a bias voltage generating circuit. The voltage boost circuit generates a control voltage at a control end of the power switch by boosting a base voltage. The discharge circuit provides a discharge path between the control end of the power switch and a reference ground end according to a bias voltage. The bias voltage generating circuit compares an output voltage on an output end of the power switch with the control voltage to generate a comparison result, and generates the bias voltage according to the comparison result.

A control device of a power switch includes a voltage boost circuit, a discharge circuit and a bias voltage generating circuit. The voltage boost circuit generates a control voltage at a control end of the power switch by boosting a base voltage. The discharge circuit provides a discharge path between the control end of the power switch and a reference ground end according to a bias voltage. The bias voltage generating circuit compares an output voltage on an output end of the power switch with the control voltage to generate a comparison result, and generates the bias voltage according to the comparison result.

An alarm output circuit can cope with simultaneous generations of a plurality of alarm factors based on alarm signals output from one output terminal. The alarm output circuit notifies externally of generations of alarm factors in an intelligent power module. A digital/analog converter, into which digital data indicating the presences and absences of generations of the alarm factors is input, outputs corresponding voltages. A voltage control oscillator outputs a signal of a frequency corresponding to an output voltage of the digital/analog converter.

An alarm output circuit can cope with simultaneous generations of a plurality of alarm factors based on alarm signals output from one output terminal. The alarm output circuit notifies externally of generations of alarm factors in an intelligent power module. A digital/analog converter, into which digital data indicating the presences and absences of generations of the alarm factors is input, outputs corresponding voltages. A voltage control oscillator outputs a signal of a frequency corresponding to an output voltage of the digital/analog converter.

The embodiments described herein provide systems and methods for determining the health status of a sensed switch. In general, the embodiments described herein determine a measure of a health status of the sensed switch by comparing a voltage on the sensed switch, ascertaining a first comparator state under one test condition and ascertaining a second comparator state under a second test condition. The first comparator state and the second comparator state are and then compared to determine the measure of the health status of the sensed switch.

A power breaker apparatus which performs energization and interception between a power supply and a load, includes a current measuring part which measures a current value flowing in a power line supplying electric power from the power supply to the load, an interception part disposed in the power line and including a plurality of semiconductor switches connected in parallel to each other, a control part comparing the current value measured in the current measuring part with an interception threshold value and, controlling on/off of the plurality of the semiconductor switches according to a comparison result, and a failure detection part which detects a potential on an output side of the interception part so that the control part checks for a failure of the semiconductor switches.

A power breaker apparatus which performs energization and interception between a power supply and a load, includes a current measuring part which measures a current value flowing in a power line supplying electric power from the power supply to the load, an interception part disposed in the power line and including a plurality of semiconductor switches connected in parallel to each other, a control part comparing the current value measured in the current measuring part with an interception threshold value and, controlling on/off of the plurality of the semiconductor switches according to a comparison result, and a failure detection part which detects a potential on an output side of the interception part so that the control part checks for a failure of the semiconductor switches.