System including a first inverter and a second inverter, and method for operating the system

Patent metadata

Field	Value
Publication number	US-2021359618-A1
Application number	US-202117391213-A
Country	US
Kind code	A1
Filing date	Aug 2, 2021
Priority date	Sep 22, 2016
Publication date	Nov 18, 2021
Grant date	—

Abstract

In a system and method for operating a system, which includes a first inverter which feeds a first electric motor, and a second inverter which feeds a second electric motor, the DC-voltage side connection of the first inverter is connected to the DC-voltage side connection of a rectifier which is supplied from an electrical AC-voltage supply network, the DC-voltage side connection of the second inverter is connected to the DC-voltage side connection of the rectifier, in particular, the two DC-voltage side connections of the inverters are switched in parallel, and a controller is provided, in particular in the first inverter, which controls the current accepted and acquired by the first inverter at its DC-voltage side terminal toward a setpoint value in that the torque of the first electric motor fed by the first inverter is the controlled variable.

First claim

What is claimed is:

1 . A system, comprising:
a first electric motor adapted to drive a flywheel energy store; a second electric motor; a first inverter including a DC-voltage side connection adapted to be connected to a DC-voltage side connection of a rectifier that is supplied from an electrical AC-voltage supply network, the first inverter adapted to feed the first electric motor and including a current acquisition device adapted to acquire current emerging at the DC-voltage side connection of the rectifier; a second inverter including a DC-voltage side connection adapted to be connected to the DC-voltage side connection of the rectifier, the second inverter adapted to feed the second electric motor; and a controller adapted to control the current emerging at the DC-voltage side connection of the rectifier toward a setpoint value by controlling a torque of the first electric motor.

2 . The system according to claim 1 , wherein the first electric motor is adapted to operate in a generator mode and to supply current to the second electric motor when operating in the generator mode.

3 . The system according to claim 1 , wherein the first electric motor includes a fan connected to the flywheel energy store.

4 . The system according to claim 3 , wherein the fan is adapted to generate airflow to cool the second electric motor and/or the second inverter.

5 . The system according to claim 1 , wherein the flywheel energy store includes a mass-rich fan.

6 . The system according to claim 1 , wherein the current acquisition device is adapted to acquire the current emerging at the DC-voltage side of the rectifier by summing current at the DC-voltage side connection of the first inverter and current at the DC-voltage side connection of the second inverter.

7 . The system according to claim 6 , wherein the current acquisition device is adapted to acquire the current at the DC-voltage side connection of the first inverter and to acquire the current at the DC-voltage side connection of the second inverter.

8 . The system according to claim 1 , wherein the current acquisition device is adapted to acquire the current emerging at the DC-voltage side of the rectifier by acquiring at least two phase-current values at an AC-voltage side connection of the rectifier.

9 . The system according to claim 1 , wherein the controller is adapted to determine power at the DC-voltage side connection of the rectifier and to control the power to a minimum.

10 . The system according to claim 9 , wherein the controller is adapted to determine the power at the DC-voltage side connection of the rectifier in accordance with a product of a DC voltage at the DC-voltage side connection of the rectifier and the current emerging at the DC-voltage side connection of the rectifier and/or in accordance with direct measurements of three phase currents and three phase voltages at an AC-voltage side connection of the rectifier.

11 . The system according to claim 1 , wherein the controller includes a PI controller.

12 . The system according to claim 1 , wherein the controller is adapted to acquire a rotational frequency of the first electric motor and to determine the torque of the first electric motor in accordance with the rotational frequency.

13 . The system according to claim 1 , wherein a maximum power of the second electric motor is less than a maximum power outputtable by the first electric motor.

14 . A method, comprising:
supplying an AC voltage from an electrical AC-voltage supply network to an AC-voltage side connection of a rectifier; feeding a DC voltage from a DC-voltage side connection of the rectifier to a DC-voltage side connection of a first inverter and to a DC-voltage side connection of a second inverter; acquiring current emerging at the DC-voltage side connection of the rectifier by a current acquisition device included in the first inverter; feeding a first electric motor by the first inverter; driving a flywheel energy store by the first electric motor; feeding a second electric motor by the second inverter; and controlling the current emerging at the DC-voltage side connection of the rectifier toward a setpoint value by controlling a torque of the first electric motor.

15 . The method according to claim 14 , further comprising:
operating the first electric motor in a generator mode; and supplying current from the first electric motor to the second electric motor when the first electric motor is operating in the generator mode.

16 . The method according to claim 14 , wherein the first electric motor includes a fan connected to the flywheel energy store, the method further comprising cooling the second electric motor and/or the second inverted by airflow generated by the fan.

17 . The method according to claim 14 , wherein the current emerging at the DC-voltage side of the rectifier is acquired by the current acquisition device by summing current at the DC-voltage side connection of the first inverter and current at the DC-voltage side connection of the second inverter.

18 . The method according to claim 17 , further comprising:
acquiring the current at the DC-voltage side connection of the first inverter; and acquiring the current at the DC-voltage side connection of the second inverter.

19 . The method according to claim 14 , further comprising:
determining power at the DC-voltage side connection of the rectifier; and controlling the power to a minimum.

20 . The method according to claim 14 , wherein the power is determined in accordance with a product of a DC voltage at the DC-voltage side connection of the rectifier and the current emerging at the DC-voltage side connection of the rectifier and/or in accordance with direct measurements of three phase currents and three phase voltages at an AC-voltage side connection of the rectifier.

21 . The method according to claim 14 , further comprising:
acquiring a rotational frequency of the first electric motor; and determining the torque of the first electric motor in accordance with the rotational frequency.

Assignees

• Sew Eurodrive Gmbh & Co

Inventors

• Schmidt Josef
• Zöller Thomas
• SCHäFER JENS
• Hauck Matthias

Classifications

• H02P5/74 Primary

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

• H02M5/458

  using semiconductor devices only · CPC title

• H02M1/008

  Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators · CPC title

• H02J1/16

  using energy storage units, e.g. batteries or dynamo-electric machines coupled to flywheels · CPC title

• H02P27/06

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