Claims [Claim 1]
A diagnosis apparatus for a field winding type rotating electric machine having a field winding, an armature winding, and a direct current power supply that serves as a power supply source for the field winding and the armature winding, the diagnosis apparatus being applied to a rotating electric machine that operates as a motor or a power generator, and comprising:
a diagnosis circuit that includes an internal power supply circuit having an open fault determination potential set at a different value to a positive electrode potential and a negative electrode potential of the direct current power supply so that in a fault diagnosis condition in which an induced current generated by a relative rotary motion of the armature winding does not flow through the field winding, the diagnosis circuit performs a fault diagnosis on a circuit including the field winding by measuring a voltage value of the circuit including the field winding that is generated when a current is passed through the field winding using the internal power supply circuit,
wherein, on the basis of a measurement result of the voltage value of the circuit including the field winding in the fault diagnosis condition, the diagnosis circuit:
determines that a disconnection has occurred in the circuit when the measurement result is within an open fault determination voltage range including the open fault determination potential;
determines that a power fault has occurred in the circuit when the measurement result is within a power fault determination voltage range including the positive electrode potential; and
determines that an earth fault has occurred in the circuit when the

measurement result is within an earth fault determination voltage range including the negative electrode potential.
[Claim 2]
The diagnosis apparatus for a field winding type rotating electric machine according to claim 1, wherein the field winding is drive-controlled while connected in parallel to a recirculating element by performing PWM driving on a field driving circuit that is configured by connecting a PWM switching element and the recirculating element in series to the direct current power supply,
the diagnosis circuit includes:
a first diagnosis circuit connected to a positive electrode side end portion of the field winding;
a second diagnosis circuit connected to a negative electrode side end portion of the field winding;
a diagnosis switching element that switches ON or OFF a connection between respective electrode side end portions of the recirculating element and the field winding that are not connected to the PWM switching element, among positive electrode side end portions and negative electrode side end portions of the recirculating element and the field winding;
a voltage measurement unit that measures a voltage of the positive electrode side end portion or the negative electrode side end portion of the field winding using a negative electrode voltage of the direct current power supply as a reference; and
a fault determination unit that determines the presence of the power fault, the earth fault, and the open fault in a field circuit including the field driving

circuit and the field winding on the basis of the measured voltage of the field winding, measured by the voltage measurement unit,
the first diagnosis circuit is configured to include:
a first internal power supply circuit;
a first diode that prevents a current from flowing in a direction of the first internal power supply circuit from the field winding; and
either an ejection type constant current circuit that passes a constant current from the first internal power supply circuit to the field winding or a pull-up resistor, the ejection type constant current circuit and the pull-up resistor being inserted in series between the first internal power supply circuit and the first diode,
the second diagnosis circuit is configured to include at least one of a sink type constant current circuit that passes a constant current from the field winding to a negative electrode of the direct current power supply, and a pull-down resistor,
in the fault diagnosis condition, which is a condition in which the PWM switching element and the diagnosis switching element are OFF and the induced current generated by the relative rotary motion of the armature winding does not flow through the field winding, the fault determination unit:
determines that the power fault has occurred when the measured voltage of the field winding, measured by the voltage measurement unit, is substantially equal to a positive electrode voltage of the direct current power supply;
determines that the earth fault has occurred when the measured voltage of the field winding, measured by the voltage measurement unit, is substantially equal to the negative electrode voltage of the direct current power supply; and
determines that the open fault has occurred when the measured voltage of

the field winding, measured by the voltage measurement unit, is substantially equal to the open fault determination potential, which is determined in advance in order to determine the presence of the open fault.
[Claim 3]
The diagnosis apparatus for a field winding type rotating electric machine according to claim 2, wherein the PWM switching element is connected to a positive electrode side end portion of the recirculating element,
in the fault diagnosis condition, a resistance value of the pull-down resistor is set on the basis of:
a positive electrode voltage of the first internal power supply circuit; and
a first leak current 11 that flows from a positive electrode of the direct current power supply to the field winding via the field driving circuit, and
in the fault diagnosis condition, a resistance value of the pull-up resistor is set on the basis of:
the positive electrode voltage of the first internal power supply circuit;
a voltage of the field winding in a condition where no fault has occurred;
a constant current value of the sink type constant current circuit; and
the first leak current 11 that flows from the positive electrode of the direct current power supply to the field winding via the field driving circuit.
[Claim 4]
The diagnosis apparatus for a field winding type rotating electric machine according to claim 2 or 3, wherein the PWM switching element is connected to the positive electrode side end portion of the recirculating element,
in the fault diagnosis condition, a constant current value of the ejection

type constant current circuit is set to be larger than a value obtained by subtracting a first leak current II that flows from a positive electrode of the direct current power supply to the field winding via the field driving circuit from a sum of a current flowing through the pull-down resistor and a second leak current 12 that flows from the field winding to a negative electrode of the direct current power supply, and
in the fault diagnosis condition, a constant current value of the sink type constant current circuit is set to be larger than a value of the first leak current II that flows from the positive electrode of the direct current power supply to the field winding via the field driving circuit.
[Claim 5]
The diagnosis apparatus for a field winding type rotating electric machine according to any one of claims 2 to 4, wherein the first diagnosis circuit includes the ejection type constant current circuit,
the second diagnosis circuit includes the pull-down resistor, one end of the pull-down resistor being connected to the negative electrode side end portion of the field winding and another end being connected to a negative electrode of the direct current power supply,
the voltage measurement unit measures the voltage of the positive electrode side end portion of the field winding, and
the open fault determination potential is a positive electrode voltage of the first internal power supply circuit.
[Claim 6]
The diagnosis apparatus for a field winding type rotating electric machine

according to claim 5, wherein the second diagnosis circuit further includes the sink type constant current circuit, the sink type constant current circuit being inserted in series between the pull-down resistor and the negative electrode of the direct current power supply.
[Claim 7]
The diagnosis apparatus for a field winding type rotating electric machine according to any one of claims 2 to 4, wherein the first diagnosis circuit includes the ejection type constant current circuit,
the second diagnosis circuit includes the pull-down resistor and further includes a second internal power supply circuit, the pull-down resistor pulling down the voltage of the negative electrode side end portion of the field winding to a positive electrode voltage of the second internal power supply circuit,
the voltage measurement unit measures the voltage of the negative electrode side end portion of the field winding, and
the open fault determination potential is the positive electrode voltage of the second internal power supply circuit.
[Claim 8]
The diagnosis apparatus for a field winding type rotating electric machine
according to any one of claims 2 to 4, wherein the first diagnosis circuit includes
the pull-up resistor, the pull-up resistor being inserted in series between the first
internal power supply circuit and the first diode,
the second diagnosis circuit includes the sink type constant current circuit, the voltage measurement unit measures the voltage of the positive
electrode side end portion of the field winding, and

the open fault determination potential is a positive electrode voltage of the first internal power supply circuit.
[Claim 9]
The diagnosis apparatus for a field winding type rotating electric machine according to any one of claims 2 to 8, wherein a positive electrode voltage of the first internal power supply circuit is set to be lower than a minimum value of a voltage variation range of the positive electrode voltage of the direct current power supply at which the field winding type rotating electric machine operates normally.
[Claim 10]
The diagnosis apparatus for a field winding type rotating electric machine according to any one of claims 2 to 8, wherein the first diagnosis circuit includes the ejection type constant current circuit and further includes a voltage regulation unit inserted in series between the ejection type constant current circuit and the first diode, and
in the fault diagnosis condition, the voltage regulation unit realizes an equivalent effect to that of a circuit on which a positive electrode voltage of the first internal power supply circuit is set to be lower than a minimum value of a voltage variation range of the positive electrode voltage of the direct current power supply at which the field winding type rotating electric machine operates nomially, by enlarging a potential difference between the positive electrode voltage of the first internal power supply circuit and a voltage of a wire connection end portion of the field winding.

[Claim 11]
The diagnosis apparatus for a field winding type rotating electric machine according to claim 10, wherein the voltage regulation unit is configured using a voltage regulator diode, a cathode side of which is connected to a positive electrode side of the first internal power supply circuit.
[Claim 12]
The diagnosis apparatus for a field winding type rotating electric machine according to claim 10, wherein the voltage regulation unit is configured using a diode, an anode side of which is connected to a positive electrode side of the first internal power supply circuit.
[Claim 13]
The diagnosis apparatus for a field winding type rotating electric machine according to any one of claims 2 to 12, wherein the first diagnosis circuit further includes a first switch that switches a connection in the first diagnosis circuit between a positive electrode of the first internal power supply circuit and the positive electrode side end portion of the field winding ON or OFF,
the second diagnosis circuit further includes a second switch that switches a connection in the second diagnosis circuit between the negative electrode of the direct cuirent power supply and the negative electrode side end portion of the field winding ON or OFF, and
the first switch and the second switch are switched OFF when the diagnosis switching element is ON, and switched ON when the diagnosis switching element is OFF.

[Claim 14]
The diagnosis apparatus for a field winding type rotating electric machine according to any one of claims 2 to 13, wherein when the positive electrode voltage of the direct current power supply is equal to or lower than a voltage of a wire connection end portion of the field winding in the fault diagnosis condition, the fault determination unit does not determine the presence of the power fault.
[Claim 15]
The diagnosis apparatus for a field winding type rotating electric machine according to any one of claims 2 to 14, wherein in the fault diagnosis condition, the fault determination unit determines that a breakdown has occurred in a second switching element, which is a switching element among the PWM switching element and the diagnosis switching element that is connected to a negative electrode of the direct current power supply, when the measured voltage of the field winding is higher than the negative electrode voltage of the direct current power supply in a case where the second switching element is ON, or when the measured voltage of the field winding is substantially equal to the negative electrode voltage of the direct current power supply in a case where the second switching element is OFF, and
determines that a breakdown has occurred in a first switching element, which is a switching element among the PWM switching element and the diagnosis switching element that is connected to a positive electrode of the direct current power supply, when the measured voltage of the field winding is lower than the positive electrode voltage of the direct current power supply in a case where the first switching element is ON, or when the measured voltage of the field winding is substantially equal to the positive electrode voltage of the

direct current power supply in a case where the first switching element is OFF.
[Claim 16]
The diagnosis apparatus for a field winding type rotating electric machine according to claim 15, wherein the fault determination unit implements a breakdown diagnosis on the second switching element first, among the first switching element and the second switching element.
[Claim 17]
A diagnosis method for a field winding type rotating electric machine, the method being used in the diagnosis apparatus for a field winding type rotating electric machine according to claim 1,
the method comprising the steps of using, in the fault diagnosis condition, the diagnosis circuit and on the basis of the measurement result of the voltage value of the circuit including the field winding in the fault diagnosis condition:
determining that a disconnection has occurred in the circuit when the measurement result is within an open fault determination voltage range including the open fault determination potential;
determining that a power fault has occurred in the circuit when the measurement result is within a power fault determination voltage range including the positive electrode potential; and
determining that an earth fault has occurred in the circuit when the measurement result is within an earth fault determination voltage range including the negative electrode potential.