DE-102024133134-A1 - Control circuit and drive arrangement

Abstract

The invention provides a drive arrangement (10) that can be flexibly adapted to different operating conditions and thus operated efficiently, as well as a control circuit (11) for the drive arrangement (10). For this purpose, the control circuit (11) comprises a first inverter (12) for connection to an electric motor (16) of the drive arrangement (10) and a second inverter (14) for connection to the electric motor (16), wherein a voltage converter (18) is connected upstream of the second inverter (14).

Inventors

• Raphael Oestreicher

Assignees

• DR. ING. H.C. F. PORSCHE AKTIENGESELLSCHAFT

Dates

Publication Date

20260513

Application Date

20241113

Claims (8)

1. Control circuit (11) for a three-phase electric motor (16), wherein the control circuit (11) comprises a first converter (12) for connection to the electric motor (16) and a second converter (14) for connection to the electric motor (16), characterized in that a voltage converter (18) is connected upstream of the second converter (14).
2. Control circuit according to the preceding claim, characterized in that the first converter (12) and the voltage converter (18) are connected in parallel.
3. Control circuit according to one of the preceding claims, characterized in that the voltage converter (18) is designed as a DC-DC converter.
4. Control circuit according to one of the preceding claims, characterized in that the voltage converter (18) is adjustable.
5. Control circuit according to one of the preceding claims, characterized in that the first inverter (12) and the voltage converter (18) are supplied by two different voltage sources, for example two different battery voltages (VDC).
6. Control circuit according to one of the preceding claims, characterized in that the voltage converter (18) comprises a buck converter and/or a cuk converter.
7. Control circuit according to one of the preceding claims, characterized in that the control circuit (11) is configured to adjust the voltage converter (18) depending on an operating point of the electric motor (16).
8. Drive arrangement (10) for a battery electric vehicle, in particular a motor vehicle, comprising a control circuit (11) according to one of the preceding claims and an electric motor (16) connected to the control circuit (11).

Description

The present invention relates to a control circuit for a three-phase electric motor and a drive arrangement for a battery-electric vehicle. State of the art CN113422558A This describes a variable drive circuit for an open-winding motor with two inverters. A switching tube is located between the inverters on the DC bus. Controlling the switching tube allows switching between three-phase inverter drive control and the open-winding motor drive circuit. At motor speeds below 30% of the rated power, the traditional three-phase inverter configuration is used. At speeds between 30% and 100% of the rated power, the first inverter is connected to the DC power source, while the switching tubes on the common DC bus are disconnected, and the DC output of the second inverter is connected only to a capacitor. DE102022210547A1 This describes a solution in which multiple inverters are used to drive a single electric machine with multiple winding systems. The inverters and the inductances provided by the winding system are operated as DC-DC converters. A control circuit allows the DC-DC converters to be operated in a nested configuration. The voltages supplied to the DC terminals of the inverters are balanced to ensure that a predetermined voltage, in this case 800 V, is evenly distributed among them. In the event of a fault, the control system can operate with a reduced number of phases, thus enabling fail-safe operation. KR102512192B1 This describes another inverter system based on an open-winding motor system that can change modes via switch control. The system can operate as a bidirectional 3-phase DC/DC buck or boost converter, or as a boost converter from a DC charging port to a battery. CN107791875A proposes connecting a capacitor in parallel between the output side of a three-phase AC/DC rectifier and the input side of a three-phase DC/DC converter. The three-phase alternating current flows into the neutral point of the six-phase winding of an open-end motor to charge a battery at the rectifier's output. US20190097534A1 This describes an inverter for an HVACR system that includes a boost converter and a variable-speed electric machine. The controller is configured to control the boost converter based on the machine's load and generate one of two boosted voltages. US20230079383A1 This describes an electric drive train in which an adjustable DC/DC converter is placed between the battery and the inverter. In an open-end configuration, a zero-phase current is superimposed on the drive current. Disclosure of the invention For battery-electric machines, the efficiency of converting electrical power into mechanical power is a crucial characteristic. This is particularly relevant for the efficiency of battery-electric vehicles, which significantly impacts their maximum range. However, the efficiency of an electric machine also depends on the operating point at which it is operated and how it is controlled. This applies particularly to three-phase electric machines, which are common, for example, in high-performance applications such as powering battery-electric vehicles. The object of the present invention is therefore to offer devices with which a three-phase electric machine can be operated flexibly at different operating points. The problem is solved first by a control circuit for a three-phase electric motor, wherein the control circuit includes a first converter for connection to the electric motor and a second converter for connection to the electric motor, with a voltage converter connected upstream of the second converter. One underlying idea here is to control the electric motor in a circuit with an open end, a so-called "open end winding" circuit. Inverters, specifically the first and second inverters, are provided at both the motor input and output. The electric motor can be operated depending on the design and configuration of the first and second inverters. Another idea is to connect a voltage converter before the second inverter. The second inverter would then be powered by an intermediate circuit. The voltage supplied can differ from the input voltage of the voltage converter. This makes it possible to modify the conversions of the second converter in a cost-effective manner. For example, if the voltage converter is a buck converter, the output voltage of the second converter can be reduced by the voltage converter. If the voltage converter is a boost converter, the output voltage of the second converter can be increased by the voltage converter in a similar way. By adjusting the output voltage of the second inverter, the effective voltage with which the electric motor is operated, which corresponds to a differential voltage of the three-phase currents provided by the first and second inverters, can be set. The effective voltage can be set for a specific operating condition, such as a particular speed of the electric motor. Under this operating condition, the electric motor can thus be operated particularly e