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

Patent metadata

Field	Value
Publication number	US-11081997-B2
Application number	US-201716461845-A
Country	US
Kind code	B2
Filing date	Dec 26, 2017
Priority date	Jan 20, 2017
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

A power conversion device includes a first inverter connected to first ends of windings of each phase of a motor, a second inverter connected to second ends of the windings of each phase, a first phase separation relay circuit to switch between connection and disconnection between the first ends of the windings of each phase and the first inverter, a second phase separation relay circuit to switch between connection and disconnection between the second ends of the windings of each phase and the second inverter, a sub-inverter circuit connectable to the first ends and the second ends of the windings of each phase, a third phase separation relay circuit to switch between connection and disconnection between the first ends of the windings of each phase and the sub-inverter circuit, and a fourth phase separation relay circuit to switch between connection and disconnection between the second ends of the windings of each phase and the sub-inverter circuit.

First claim

The invention claimed is:

1. A power conversion device that converts power from a power supply to power supplied to a motor having n-phase windings where n is an integer of 3 or more, the power conversion device comprising:
a first inverter connected to first ends of the windings of each phase of the motor;
a second inverter connected to second ends of the windings of each phase;
a first phase separation relay circuit to switch between connection and disconnection between the first ends of the windings of each phase and the first inverter;
a second phase separation relay circuit to switch between connection and disconnection between the second ends of the windings of each phase and the second inverter;
a sub-inverter circuit connectable to the first ends and the second ends of the windings of each phase;
a third phase separation relay circuit to switch between connection and disconnection between the first ends of the windings of each phase and the sub-inverter circuit; and
a fourth phase separation relay circuit to switch between connection and disconnection between the second ends of the windings of each phase and the sub-inverter circuit.

2. The power conversion device according to claim 1 , wherein:
the first phase separation relay circuit includes n switching elements to switch between connection and disconnection between the first ends of the windings of each phase and the first inverter;
the second phase separation relay circuit includes n switching elements to switch between connection and disconnection between the second ends of the windings of each phase and the second inverter;
the third phase separation relay circuit includes n switching elements to switch between connection and disconnection between the first ends of the windings of each phase and the sub-inverter circuit; and
the fourth phase separation relay circuit includes n switching elements to switch between connection and disconnection between the second ends of the windings of each phase and the sub-inverter circuit.

3. The power conversion device according to claim 2 , wherein each of the n switching elements in each of the first, second, third and fourth phase separation relay circuits is a semiconductor switching element including a freewheeling diodes, and n freewheeling diodes in each circuit are directed in a same direction.

4. The power conversion device according to claim 3 , wherein each of the n switching elements in each of the first, second, third, and fourth phase separation relay circuits are arranged such that a forward current flows in the freewheeling diodes toward the motor.

5. The power conversion device according to claim 1 , wherein:
bridge circuits of the first and second inverters each include n legs each including a low side switching element and a high side switching element;
the sub-inverter circuit includes a single leg including a low side switching element and a high side switching element;
the first ends of the windings of each phase are connected to n nodes between the low side switching element and the high side switching element in the bridge circuit of the first inverter via the first phase separation relay circuit and are connected to a node between the low side switching element and the high side switching element in the leg of the sub-inverter circuit via the third phase separation relay circuit; and
the second ends of the windings of each phase are connected to n nodes between the low side switching element and the high side switching element in the bridge circuit of the second inverter via the second phase separation relay circuit and are connected to a node between the low side switching element and the high side switching element in the leg of the sub-inverter circuit via the fourth phase separation relay circuit.

6. The power conversion device according to claim 1 , wherein:
bridge circuits of the first and second inverters each include n legs each including a low side switching element and a high side switching element;
the sub-inverter circuit includes two legs each including a low side switching element and a high side switching element;
the first ends of the windings of each phase are connected to n nodes between the low side switching element and the high side switching element in the bridge circuit of the first inverter via the first phase separation relay circuit;
at least one of the first ends of the windings of each phase is connected to a node between the low side switching element and the high side switching element in one of the two legs of the sub-inverter circuit via the third phase separation relay circuit, and the remaining first ends of the windings of each phase are connected to a node between the low side switching element and the high side switching element in the other one of the two legs of the sub-inverter circuit via the third phase separation relay circuit;
the second ends of the windings of each phase are connected to n nodes between the low side switching element and the high side switching element in the bridge circuit of the second inverter via the second phase separation relay circuit; and
at least one of the second ends of the windings of each phase is connected to the node in the one leg of the sub-inverter circuit via the fourth phase separation relay circuit, and the remaining second ends of the windings of each phase are connected to the node in the other leg of the sub-inverter circuit via the fourth phase separation relay circuit.

7. The power conversion device according to claim 1 , wherein:
bridge circuits of the first and second inverters each include n legs each including a low side switching element and a high side switching element;
the sub-inverter circuit includes a leg for the first inverter, the leg including a low side switching element and a high side switching element, and a leg for the second inverter, the leg including a low side switching element and a high side switching element;
the first ends of the windings of each phase are connected to n nodes between the low side switching element and the high side switching element in the bridge circuit of the first inverter via the first phase separation relay circuit and are connected to a node between the low side switching element and the high side switching element in the leg for the first inverter of the sub-inverter circuit via the third phase separation relay circuit; and
the second ends of the windings of each phase are connected to n nodes between the low side switching element and the high side switching element in the bridge circuit of the second inverter via the second phase separation relay circuit and are connected to a node between the low side switching element and the high side switching element in the leg for the second inverter of the sub-inverter circuit via the fourth phase separation relay circuit.

8. The power conversion device according to claim 1 , wherein:
bridge circuits of the first and second inverters each include n legs each including a low side switching element and a high side switching element;
the sub-inverter circuit includes n legs each including a low side switching element and a high side switching element;
the first ends of the windings of each phase are connected to n nodes between the low side switching element and the high side switching element in the bridge circuit of the first inverter via the first phase separation relay circuit and are connected to n nodes between the low side switching element and the high side switching element in the sub-inverter circuit via the third phase separation relay circuit; and
the second ends of the windings of each phase are connected to n nodes between the low side switching element and the high side switching element in the bridge circuit of t

Assignees

• Nidec Corp

Inventors

• Ohashi Hiromitsu

Classifications

• H02P29/028

  the motor continuing operation despite the fault condition, e.g. eliminating, compensating for or remedying the fault · CPC title

• B62D5/0484

  for reaction to failures, e.g. limp home · CPC title

• H02P27/08 Primary

  with pulse width modulation · CPC title

• H02M7/53871 Primary

  with automatic control of output voltage or current · CPC title

• H02P27/06

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