Electric motor and air-conditioning apparatus including the same

Patent metadata

Field	Value
Publication number	US-12088227-B2
Application number	US-202017785951-A
Country	US
Kind code	B2
Filing date	Feb 19, 2020
Priority date	Feb 19, 2020
Publication date	Sep 10, 2024
Grant date	Sep 10, 2024

Abstract

An electric motor has a mechanism to detect an overcurrent in an inverter circuit. The electric motor includes a rotor, a stator, and a board. The board includes a power transistor, a first resistor, a second resistor, and a constant voltage diode. The power transistor is included in the inverter circuit, which is configured to change a direction of a current that flows through a winding of the stator. The first resistor is provided between the power transistor and a ground terminal, and configured to detect an overcurrent in the inverter circuit. The second resistor is provided between the power transistor and the first resistor, and configured to detect a current that flows through the winding of the stator. The constant voltage diode is connected parallel to the first resistor.

First claim

The invention claimed is:

1. An electric motor comprising:
a rotor;
a stator; and
a board,
wherein
the board includes
a power transistor included in an inverter circuit configured to change a direction of a current that flows through a winding of the stator,
a first resistor provided between the power transistor and a ground terminal, and configured to detect an overcurrent in the inverter circuit,
a second resistor provided between the power transistor and the first resistor, and configured to detect a current that flows through the winding of the stator, and
a constant voltage diode connected parallel to the first resistor.

2. The electric motor of claim 1 , further comprising an amplifier circuit configured to amplify a voltage value of the second resistor,
wherein the amplifier circuit includes an operational amplifier.

3. The electric motor of claim 2 , wherein the operational amplifier is a rail-to-rail operational amplifier.

4. The electric motor of claim 2 , further comprising a controller configured to control the inverter circuit,
wherein the controller and the amplifier circuit are supplied with power from a single power supply.

5. The electric motor of claim 2 , wherein
the amplifier circuit includes a third resistor between the operational amplifier and an input terminal of the amplifier circuit, and
a ratio of a resistance value of the second resistor to a resistance value of the third resistor is higher than a ratio of a voltage of a power supply for the amplifier circuit to a voltage of a bus power supply.

6. The electric motor of claim 1 , wherein a resistance value of the first resistor is higher than one-third of a resistance value of the second resistor.

7. The electric motor of claim 1 , wherein the resistance value of the second resistor is lower than or equal to 1Ω.

8. The electric motor of claim 1 , wherein
one side of the board faces end faces of the stator and the rotor in an axial direction of the rotor, and
the constant voltage diode is provided on an other side of the board.

9. The electric motor of claim 1 , wherein an output of the electric motor is higher than or equal to 100 W.

10. The electric motor of claim 1 , wherein
the board is provided with a lead-in portion that is connected to a lead, and
the lead-in portion is provided on one side of the board, and the first resistor is provided on an other side of the board that is opposite to the one side.

11. An air-conditioning apparatus comprising the electric motor of claim 1 .

Assignees

• Mitsubishi Electric Corp

Inventors

• Oya Junichiro
• Yamamoto Mineo
• Ishii Hiroyuki
• Urabe Yuto

Classifications

• H02P29/00

  Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors (arrangements for starting electric motors H02P1/00; arrangements for stopping or slowing electric motors H02P3/00; control of motors that can be connected to two or more different electric power supplies H02P4/00; regulating or controlling the speed or torque of two or more electric motors H02P5/00; vector control H02P21/00) · CPC title

• H02K11/33

  Drive circuits, e.g. power electronics (H02K11/38 takes precedence) · CPC title

• H02P27/06 Primary

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

• H02P29/027 Primary

  the fault being an over-current · CPC title