Vehicle or environment-controlled unit having a multiphase alternator with a protected high-voltage bus
View Patent ↗A mobile environment-controlled unit, such as an over-the-road compartment trailer, having an environmental-control system, such as a refrigeration unit, powered by an alternator and having a high-voltage alternating current (AC) bus. The unit incorporates a high resistance ground scheme and can incorporate a solid-state input module to detect phase-chassis faults. This combination provides an improvement in protection for mobile applications that cannot have a voltage reference (or neutral point) solidly connected to earth ground.
1. A mobile environment-controlled unit comprising:
a chassis;
a compartment supported by the chassis; and
an environmental-control system supported by the chassis and in environmental communication with the compartment, the environmental-control system being configured to control an environmental parameter of the compartment, the environmental-control system including
a multiphase alternator powered by an internal combustion engine and to supply electrical power for the environmental-control system, the alternator having phase windings and a neutral point for the phase windings; and
a high-resistance resistor electrically coupling the neutral point for the phase windings to the chassis.
2. The mobile environment-controlled unit of claim 1 , wherein the environmental-control system further includes
a solid-state module electrically coupling the neutral point for the phase windings to the chassis, the module being configured to monitor a voltage from the neutral point to the system chassis, and to provide an output when the monitored voltage indicates a possible phase-to-structure fault.
3. The mobile environment-controlled unit of claim 1 , wherein the environmental-control system further includes
a controller configured to control the environmental-control system for affecting the environment of the compartment.
4. The mobile environment-controlled unit of claim 1 , wherein the high-resistance resistor has a value in a range sufficient to limit current in a possible phase-to-chassis fault and to dissipate parasitic current during a possible intermittent phase-to-chassis fault.
5. The mobile environment-controlled unit of claim 1 , wherein the high-resistance resistor has a value between 1 kΩ and 1 MΩ.
6. The mobile environment-controlled unit of claim 1 , wherein the high-resistance resistor has a value between 10 kΩ and 100 kΩ.
7. The mobile environment-controlled unit of claim 1 , wherein the high-resistance resistor has a value between 30 kΩ and 70 kΩ.
8. The mobile environment-controlled unit of claim 1 , wherein the alternator is a three-phase alternator with the phase windings configured in a wye arrangement, and wherein the neutral point is the center of the wye arrangement.
9. A vehicle comprising:
a chassis;
a multiphase alternator powered by an internal combustion engine and to supply electrical power for the environmental-control system, the alternator having phase windings and a neutral point for the phase windings; and
a high-resistance resistor electrically coupling the neutral point for the phase windings to the chassis.
10. The vehicle of claim 9 , and further comprising:
a solid-state module electrically coupling the neutral point for the phase windings to the chassis, the module being configured to monitor a voltage related to the neutral point for the phase windings and the system chassis, and to provide an output when the monitored voltage indicates a possible phase-to-structure fault.
11. The vehicle of claim 9 , and further comprising:
a controller configured to control the environmental-control system for affecting the environment of the compartment.
12. The vehicle of claim 9 , wherein the high-resistance resistor has a value in a range sufficient to limit current in a possible phase-to-chassis fault and to dissipate parasitic current during a possible intermittent phase-to-chassis fault.
13. The vehicle of claim 9 , wherein the range of the high-resistance resistor is between 30 kΩ and 70 kΩ.
14. The vehicle of claim 9 , wherein the alternator is a three-phase alternator with the phase windings configured in a wye arrangement, and wherein the neutral point is the center of the wye arrangement.
15. A mobile environment-controlled unit comprising:
a chassis;
a compartment supported by the chassis;
an environmental-control system supported by the chassis and in environmental communication with the compartment, the environmental-control system being configured to control an environmental parameter of the compartment, the environmental-control system including
an internal combustion engine;
a three-phase alternator to be powered by the internal combustion engine and to supply electrical power to the environmental-control system, the alternator having phase windings in a wye arrangement and a neutral point for the phase windings;
a high-resistance resistor electrically coupling the neutral point for the phase windings to the chassis, the high-resistance resistor having a value in a range sufficient to limit current in a possible phase-to-chassis fault and to dissipate parasitic current during a possible intermittent phase-to-chassis fault;
a solid-state module electrically coupling the neutral point for the phase windings to the chassis, the module being configured to monitor a voltage from the neutral point for the phase windings to the system chassis, and to provide an output when the monitored voltage indicates a possible phase-to-structure fault.
16. The mobile environment-controlled unit of claim 15 , wherein the environmental-control system further includes
a controller configured to control the environmental-control system for affecting the environment of the compartment, to receive the output from the solid-state module, and to control the environment-control system based on the output.
17. The mobile environment-controlled unit of claim 15 , wherein the range of the high-resistance resistor is between 30 kΩ and 70 kΩ.