Device for driving a plurality of motors and electric apparatus including the same

Patent metadata

Field	Value
Publication number	US-11329578-B2
Application number	US-202016987628-A
Country	US
Kind code	B2
Filing date	Aug 7, 2020
Priority date	Aug 8, 2019
Publication date	May 10, 2022
Grant date	May 10, 2022

Abstract

A device for driving a plurality of motors and an electric apparatus having the same is disclosed. The device includes an inverter connected to a DC terminal, a multi-phase motor connected to the inverter, a single-phase motor serially connected to the multi-phase motor, and a first capacitor and a second capacitor connected in series between a first end and a second end of the DC terminal, wherein the single-phase motor is connected to the multi-phase motor, and a node between the first capacitor and the second capacitor. Accordingly, a plurality of motors serially connected with each other can be driven by using a single inverter.

First claim

What is claimed is:

1. A device for driving a plurality of motors, the device comprising:
an inverter electrically connected to a first end and a second end of a DC terminal;
a multi-phase motor electrically connected to the inverter;
a single-phase motor electrically connected in series with the multi-phase motor; and
a first capacitor and a second capacitor electrically connected in series between the first end and the second end of the DC terminal,
wherein the single-phase motor is electrically connected to a node between the first capacitor and the second capacitor.

2. The device of claim 1 , wherein a neutral point of the multi-phase motor is electrically connected to a first end of the single phase motor, and
a second end of the single-phase motor is electrically connected to the node between the first capacitor and the second capacitor.

3. The device of claim 1 , wherein an input terminal of the single-phase motor and each phase of the multi-phase motor are electrically connected to a common node, and
an output terminal of the single-phase motor is connected to the node between the first capacitor and the second capacitor.

4. The device of claim 1 , wherein a neutral point of the multi-phase motor is electrically connected to a first end of the single phase motor, and
a DC terminal neutral point comprising the node between the first capacitor and the second capacitor, is connected to a second end of the single-phase motor.

5. The device of claim 4 , wherein the neutral point of the multi-phase motor comprises a node having zero current based on a phase difference in a multi-phase AC system.

6. The device of claim 1 , further comprising:
a first current detector configured to detect a first current input to the multi-phase motor; and
a second current detector configured to detect a second current input to the single-phase motor.

7. The device of claim 1 , further comprising:
a first voltage detector configured to detect a DC voltage across the first capacitor; and
a second voltage detector configured to detect a DC voltage across the second capacitor.

8. The device of claim 1 , further comprising a controller configured to control the inverter, the controller being configured to drive one of:
the single-phase motor and the multi-phase motor at a common speed,
the single-phase motor and the multi-phase motor at different speeds,
only the single-phase motor, or
only the multi-phase motor.

9. The device of claim 8 , wherein a number of frequencies of a current input to the multi-phase motor when the single-phase motor and the multi-phase motor are driven at the common speed is greater than a number of frequencies of a current input to the multi-phase motor when the single-phase motor and the multi-phase motor driven at different speeds.

10. The device of claim 9 , wherein the number of frequencies of the current input to the multi-phase motor when the single-phase motor and the multi-phase motor are driven at the common speed is one, and
the number of frequencies of the current input to the multi-phase motor when the single-phase motor and the multi-phase motor are driven at different speeds is two or more.

11. The device of claim 9 , wherein a current output from the inverter when the single-phase motor and the multi-phase motor are driven at the common speed corresponds to a single sine wave, and
the current output from the inverter when the single-phase motor and the multi-phase motor are driven at different speeds corresponds to a sum of a plurality of sine waves.

12. The device of claim 8 , wherein, when the single-phase motor and the multi-phase motor are driven at the common speed, the multi-phase motor and the single-phase motor are driven by an effective current having the same frequency.

13. The device of claim 8 , wherein, when the single-phase motor and the multi-phase motor are driven at the same speed, a torque of the multi-phase motor is greater than a torque of the single-phase motor when a maximum level of an effective current of the multi-phase motor and a maximum level of an effective current of the single-phase motor are the same.

14. The device of claim 8 , wherein, when the single-phase motor and the multi-phase motor are driven at different speeds, a current through the multi-phase motor is different from a current through the single-phase motor, and
when driving only the multi-phase motor, a current flows through the multi-phase motor, and no current flows through the single-phase motor.

15. The device of claim 8 , wherein, when driving only the multi-phase motor, an electric potential between the motor neutral point of the multi-phase motor, and a DC terminal neutral point between the first capacitor and the second capacitor is the same.

16. The device of claim 8 , wherein, when the single-phase motor and the multi-phase motor are driven at different speeds, a first current having a first frequency and a second frequency is input to the multi-phase motor, and a second current having the second frequency is input to the single-phase motor, and
when the single-phase motor and the multi-phase motor are driven at the same speed, a third current having a third frequency is input to the multi-phase motor, and a fourth current having the third frequency is input to the single-phase motor.

17. The device of claim 8 , wherein, when the single-phase motor is driven, an electric potential between a motor neutral point of the multi-phase motor and a DC terminal neutral point between the first capacitor and the second capacitor is different, and
when driving only the multi-phase motor, an electric potential between the motor neutral point and the DC terminal neutral point is the same.

18. The device of claim 8 , wherein, the inverter comprises a plurality of upper switching elements and a plurality of lower switching elements, and wherein, when only the single-phase motor is driven, one of the upper switching elements or the lower switching elements are turned on.

19. An electric apparatus comprising a device for driving a plurality of motors, the device comprising:
an inverter electrically connected to a first end and a second end of a DC terminal;
a multi-phase motor electrically connected to the inverter;
a single-phase motor electrically connected in series with the multi-phase motor; and
a first capacitor and a second capacitor electrically connected in series between the first end and the second end of the DC terminal,
wherein the single-phase motor is electrically connected to a node between the first capacitor and the second capacitor.

20. The electric apparatus of claim 19 , wherein the multi-phase motor comprises a fan motor, and the single-phase motor comprises a pump motor.

Assignees

• Lg Electronics Inc

Inventors

• Kwon Sunku
• Jun Chaseung
• Choe Sehwa
• Lee Wookjin

Classifications

• H02P27/08

  with pulse width modulation · CPC title

• H02P5/74 Primary

  controlling two or more AC dynamo-electric motors (H02P5/46, H02P5/60 take precedence) · CPC title

• H02P27/085

  wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency · CPC title

• H02P21/22

  Current control, e.g. using a current control loop · CPC title

• H02P5/50 Primary

  by comparing electrical values representing the speeds · CPC title