Power conversion device, motor drive unit, electric power steering device, and relay module

Patent metadata

Field	Value
Publication number	US-11014602-B2
Application number	US-201716082160-A
Country	US
Kind code	B2
Filing date	Mar 1, 2017
Priority date	Mar 4, 2016
Publication date	May 25, 2021
Grant date	May 25, 2021

Abstract

A power conversion device may include a first inverter to which a first end of each phase winding of the electric motor is coupled; a second inverter to which a second end of each phase winding is coupled; a first phase isolation relay circuit structured to switch between connection and disconnection of the one end of each phase winding to and from the first inverter; and a first neutral point relay circuit to which the one end of each phase winding is coupled and which is structured to switch between connection and disconnection of the one end of each phase winding to and from the one end of each other phase winding.

First claim

The invention claimed is:

1. A power conversion device for converting power from a power source into power that is to be supplied to a motor having n phase windings, n being an integer of three or more, the device comprising:
a first inverter to which a first end of each phase winding of the motor is coupled;
a second inverter to which the second end of each phase winding is coupled; and
at least n relays structured to switch between connection and disconnection of the first end of each of the n phase windings to and from the first inverter, wherein
the first and second inverters being structured to, when operating normally, convert power from the power supply into power that is to be supplied to the motor by n-phase conduction control;
the power conversion device is structured such that, under a failure in at least one of a plurality of switching elements included in the first and second inverters, the first and second inverters convert power from the power supply into power that is to be supplied to the motor by m-phase conduction control using m phases of the n phases different from the phase of a winding coupled to the failed switching element, m being an integer of not smaller than two and smaller than n;
each of the first and second inverters comprise n legs each comprising a low-side switching element and a high-side switching element; and
the plurality of switching elements of the first and second inverters form a plurality of H-bridges,
wherein
the at least n relays are coupled between the first end of each of the n phase windings and the n legs of the first invertor forming the H-bridges, and the second end of each of the n phase windings are coupled to the n legs of the second inverter forming the H-bridges,
the power conversion device further comprises circuit structured to perform n-phase conduction control on the first and second inverters,
the power conversion device is structured such that, under a failure in at least one of a plurality of switching elements included in the first and second inverters, the control circuit changes the control of the first and second inverters from the n-phase conduction control to the m-phase conduction control, and
the power conversion device further comprises n relays each of which is structured to switch between connection and disconnection of the second end of the corresponding one of the n phase windings to and from the second inverter.

2. The power conversion device of claim 1 , wherein
the power conversion device is structured such that, under a failure in at least one of a plurality of switching elements included in the first and second inverters, one of the at least n relays that switches between connection and disconnection of one of the n phase windings coupled to the failed switching element to and from the first inverter, is turned off, and at least m of the at least n relays different from the relay turned off are turned on.

3. The power conversion device of claim 1 , wherein
the power conversion device is structured such that, under a failure in a switching element included in the first inverter, power from the power supply is converted into power that is to be supplied to the motor, using 2m legs different from a failed leg including the failed switching element and a leg of the second inverter included in an H-bridge formed by the failed leg and the leg of the second inverter.

4. The power conversion device of claim 1 , wherein
the motor comprises three phase windings,
the first and second inverters being structured to, when operating normally, convert power from the power supply into power that is to be supplied to the motor, by three-phase conduction control, and
the power conversion device is structured such that, under a failure in at least one of a plurality of switching elements included in the first and second inverters, the first and second inverters convert power from the power supply into power that is to be supplied to the motor, by two-phase conduction control using the other two of the three phases different from the phase of a winding coupled to the failed switching element.

5. A motor drive unit comprising:
the electric motor;
the power conversion device of claim 1 .

6. An electric power steering device comprising:
the motor drive unit of claim 5 .

Assignees

• Nidec Corp

Inventors

• Wada Eiji
• NABESHI Kaori

Classifications

• B62D5/0481 Primary

  monitoring the steering system, e.g. failures · CPC title

• H02M1/0043

  Converters switched with a phase shift, i.e. interleaved (non-isolated DC/DC converters H02M3/1586) · CPC title

• H02M7/493 Primary

  the static converters being arranged for operation in parallel · CPC title

• H02M7/48

  using discharge tubes with control electrode or semiconductor devices with control electrode · CPC title

• H02P27/06

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title