Oil lubricant quality sensor for a lubricant supported electric motor and an oil cooled inverter

A quality diagnostics system for lubricant/coolant fluid, comprising:

• a lubricant supported electric motor including a stator and a rotor defining a gap therebetween, with the lubricant/coolant fluid disposed in the gap for supporting the rotor while allowing the rotor to rotate relative to the stator;
• an inverter including a plurality of power switches configured to supply an alternating current (AC) power to the lubricant supported electric motor for driving the rotor to rotate;
• a passageway configured to convey the lubricant/coolant fluid between the lubricant supported electric motor and the inverter;
• a lubricant quality sensor including a set of sensor plates disposed along the passageway, an excitation source configured to apply an AC excitation voltage to a first sensor plate of the set of sensor plates, and an electrical sensor configured to measure a response to the AC excitation voltage;
• the set of sensor plates including a reference plate having a reference voltage;
• and
• wherein the inverter includes a DC positive conductor and a DC negative conductor and series combination of input capacitors connected therebetween to define a midpoint node, and wherein the reference plate is connected to the midpoint node.

A quality diagnostics system for lubricant/coolant fluid, comprising:

• a lubricant supported electric motor including a stator and a rotor defining a gap therebetween, with the lubricant/coolant fluid disposed in the gap for supporting the rotor while allowing the rotor to rotate relative to the stator;
• an inverter including a plurality of power switches configured to supply an alternating current (AC) power to the lubricant supported electric motor for driving the rotor to rotate;
• a passageway configured to convey the lubricant/coolant fluid between the lubricant supported electric motor and the inverter;
• a lubricant quality sensor including a set of sensor plates disposed along the passageway, an excitation source configured to apply an AC excitation voltage to a first sensor plate of the set of sensor plates, and an electrical sensor configured to measure a response to the AC excitation voltage;
• wherein the electrical sensor is configured to measure an electrical current in a conductor attached to one of the sensor plates;
• and
• wherein the inverter includes a printed circuit board with the plurality of power switches and the electrical sensor disposed thereupon.

A quality diagnostics system for lubricant/coolant fluid in a vehicle, comprising:

• a lubricant supported electric motor including a stator and a rotor defining a gap therebetween, with the lubricant/coolant fluid disposed in the gap for supporting the rotor while allowing the rotor to rotate relative to the stator;
• a passageway configured to convey the lubricant/coolant fluid between the lubricant supported electric motor and one or more other components;
• a lubricant quality sensor including a set of sensor plates disposed along the passageway and an excitation source configured to supply an AC excitation voltage to at least one sensor plate of the set of sensor plates;
• a controller configured to cause the excitation source to apply the AC excitation voltage to the at least one sensor plate;
• an electrical sensor configured to measure an electrical response to the application of the AC excitation voltage;
• and
• the controller further configured to determine, based on a sensor signal from the electrical sensor, at least one of metal contamination and water contamination in the lubricant/coolant fluid;
• and
• an inverter including a plurality of power switches configured to supply an alternating current power to the lubricant supported electric motor for driving the rotor to rotate, and wherein the plurality of power switches in the inverter are further configured to function as the excitation source for applying the AC excitation to the at least one sensor plate of the set of sensor plates.

A method for sensing contaminants in a lubricant/coolant fluid of a lubricant supported electric motor, comprising:

• circulating the lubricant/coolant fluid through a passageway and to the lubricant supported electric motor;
• applying, by an excitation source, an AC excitation voltage to a first sensor plate disposed adjacent to and along the passageway;
• and
• sensing, by an electrical sensor, a response to the application of the AC excitation voltage;
• determining, based on the response to the application of the AC excitation voltage, at least one of metal contamination and water contamination in the lubricant/coolant fluid;
• and
• supplying, by a plurality of power switches of an inverter, an alternating current (AC) power to the lubricant supported electric motor for causing a rotor thereof to rotate, and wherein the plurality of power switches of the inverter also function as the excitation source to apply the AC excitation voltage to the first sensor plate.