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

Patent metadata

Field	Value
Publication number	US-10778084-B2
Application number	US-201716082152-A
Country	US
Kind code	B2
Filing date	Mar 1, 2017
Priority date	Mar 4, 2016
Publication date	Sep 15, 2020
Grant date	Sep 15, 2020

Abstract

A power conversion device according to an embodiment of the present invention includes a first inverter to which one end of each of n phase windings (n is an integer of three or more) included in an electric motor is coupled, a second inverter to which the other end of each phase winding is coupled, and a switch circuit having at least one of: a first switch element that switches between connection and disconnection of the first inverter and ground, and a second switch element that switches between connection and disconnection of the second inverter and ground.

First claim

The invention claimed is:

1. A power conversion device for converting power that is to be supplied to an electric 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 electric motor is coupled;
a second inverter to which a second end of each phase winding is coupled; and
a switch circuit comprising:
a first switch element structured to switch between connection and disconnection of the first inverter and ground;
a second switch element structured to switch between connection and disconnection of the second inverter and ground;
a third switch element structured to switch between connection and disconnection of the first inverter and a power supply; and
a fourth switch element structured to switch between connection and disconnection of the second inverter and the power supply,

wherein the first and second inverters each comprise a bridge circuit comprising n legs each comprising a low-side switching element and a high-side switching element,
the power conversion device further comprises a drive circuit structured to, under a failure in one of the high-side switching elements of the first inverter, supply a control signal for turning on the n low-side switching elements to the n low-side switching elements, and
a voltage of the control signal of the drive circuit supplied to the n low-side switching elements is greater than a voltage of a control signal of the drive circuit for turning on the n low-side switching elements when the first inverter is operating normally.

2. The power conversion device of claim 1 , wherein
the third switch element is structured such that, when the first inverter is not operating normally, the third switch element disconnects the first inverter from the power supply;
the first inverter is structured such that, when the first inverter is not operating normally, a neutral point for the n phase windings is formed in the first inverter.

3. The power conversion device of claim 1 , wherein
the power conversion device is structured such that, under an open-circuit failure in the third switch element, the second and fourth switch elements are turned on, the first switch element is turned off, all the n high-side switching elements in the bridge circuit of the first inverter are turned off, and all the n low-side switching elements in the bridge circuit of the first inverter are turned on.

4. The power conversion device of claim 1 , wherein
the power conversion device is structured such that, under an open-circuit failure in the third switch element, the second and fourth switch elements are turned on, all the n high-side switching elements in the bridge circuit of the first inverter are turned on, and all the n low-side switching elements in the bridge circuit of the first inverter are turned off.

5. The power conversion device of claim 1 , wherein
the power conversion device is structured such that, under an open-circuit failure in the third switch element, the second and fourth switch elements are turned on, the first switch element is turned off, at least one of the n high-side switching elements in the bridge circuit of the first inverter is turned on, and all the n low-side switching elements in the bridge circuit of the first inverter are turned on.

6. The power conversion device of claim 1 , wherein
the power conversion device is structured such that, under a short-circuit failure in the third switch element, the second and fourth switch elements are turned on, the first switch element is turned off, all the n high-side switching elements in the bridge circuit of the first inverter are turned off, and all the n low-side switching elements in the bridge circuit of the first inverter are turned on.

7. The power conversion device of claim 1 , wherein
the power conversion device is structured such that, under an open-circuit failure in the first switch element, the second and fourth switch elements are turned on, the third switch element is turned off, all the n high-side switching elements in the bridge circuit of the first inverter are turned on, and all the n low-side switching elements in the bridge circuit of the first inverter are turned off.

8. The power conversion device of claim 1 , wherein
the power conversion device is structured such that, under an open-circuit failure in the first switch element, the second and fourth switch elements are turned on, the third switch element is turned off, all the n high-side switching elements in the bridge circuit of the first inverter are turned on, and at least one of the n low-side switching elements in the bridge circuit of the first inverter is turned on.

9. The power conversion device of claim 1 , wherein
the power conversion device is structured such that, under a short-circuit failure in the first switch element, the second and fourth switch elements are turned on, the third switch element is turned off, all the n high-side switching elements in the bridge circuit of the first inverter are turned on, and all the n low-side switching elements in the bridge circuit of the first inverter are turned off.

10. The power conversion device of claim 1 , wherein
the power conversion device is structured such that, when the first inverter is operating normally, a voltage of a first control signal for turning on the n high-side switching elements is greater than a voltage of a second control signal for turning on the n low-side switching elements, and
the power conversion device is structured such that, under a failure in one of the high-side switching elements of the first inverter, the drive circuit supplies the first control signal to the n low-side switching elements.

11. The power conversion device of claim 1 , wherein
the drive circuit includes an open-collector output type transistor.

12. A motor drive unit comprising:
the electric motor;
the power conversion device of claim 1 ; and
a control circuit that controls the power conversion device.

13. An electric power steering device comprising:
the motor drive unit of claim 12 .

14. A power conversion device for converting power that is to be supplied to an electric 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 electric motor is coupled;
a second inverter to which a second end of each phase winding is coupled; and
a switch circuit comprising:
a first switch element structured to switch between connection and disconnection of the first inverter and ground;
a second switch element structured to switch between connection and disconnection of the second inverter and ground;
a third switch element structured to switch between connection and disconnection of the first inverter and a power supply; and
a fourth switch element structured to switch between connection and disconnection of the second inverter and the power supply,

wherein the first and second inverters each comprise a bridge circuit comprising n legs each comprising a low-side switching element and a high-side switching element,
the power conversion device further comprising:
a first drive circuit structured to, when the first inverter is operating normally, supply a first control signal for turning on the n low-side switching elements, to the n low-side switching elements; and
a second drive circuit structured to, under a failure in one of the high-side switching elements of the first inverter, supply a second control signal for turning on the n low-side switching elements, to the n low-side swi

Assignees

• Nidec Corp

Inventors

• Wada Eiji

Classifications

• H02P2209/01

  Motors with neutral point connected to the power supply · CPC title

• H02P29/0241

  the fault being an overvoltage · CPC title

• H02P27/08

  with pulse width modulation · CPC title

• H02P27/06

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

• H02P25/18

  with arrangements for switching the windings, e.g. with mechanical switches or relays · CPC title