US-12620912-B2 - Electric circuit arrangement, electric drive device, motor vehicle and method for operating an electric circuit arrangement

US12620912B2US 12620912 B2US12620912 B2US 12620912B2US-12620912-B2

Abstract

An electric circuit arrangement includes at least one half bridge including two power switching elements, two driver circuits, and a discharge control circuit, wherein the half bridge is in parallel with an energy accumulator and each power switching element has a switchable section with an electric resistance that is adjustable by a control voltage at a control input of the power switching element, while in a normal operation of the power switching elements, the drivers circuits generates the control voltage at the control input of each power switching element, and, while in at least one discharge operation that discharges the energy accumulator, the discharge control circuit generates a discharge voltage as the control voltage as the control input of at least one of the power switching elements, the discharge voltage placing the at least one of the power switching elements in linear operation.

Inventors

Maximilian Schiedermeier

Assignees

AUDI AG

Dates

Publication Date: 20260505
Application Date: 20230413
Priority Date: 20220414

Claims (15)

1 . An electric circuit arrangement, comprising: at least one half bridge including two power switching elements and two driver circuits, wherein the at least one half bridge is in parallel with at least one energy accumulator and each power switching element of the power switching elements has a switchable section with an electric resistance that is adjustable by a control voltage at a control input of the power switching element, wherein, while in a normal operation of the power switching elements, the control voltage of each of the power switching elements is generated by the driver circuits; and a discharge control circuit that is different from the two driver circuits, wherein while in at least one discharge operation that discharges the at least one energy accumulator, the discharge control circuit generates a discharge voltage based on a discharge current of the at least one energy accumulator that is being discharged as the control voltage at the control input of at least one of the power switching elements, the discharge voltage placing the at least one of the power switching elements in linear operation, wherein the discharge control circuit comprises at least one discharge control device that, in operation, sets an amplitude of the discharge voltage based on discharge information, wherein the discharge control circuit, in operation, generates discharge voltages of both of the power switching elements, and the discharge control device, in operation, sets, in a freewheel discharge operation, the discharge voltages based on discharge information including two voltage metering values describing respectively a voltage drop across each of the power switching elements, and wherein the voltage drop across a first one of the power switching elements is equal to the voltage drop across a second one of the power switching elements.
2 . The electric circuit arrangement according to claim 1 , wherein the discharge control circuit includes at least one resistance arrangement connected in parallel with the control input of the at least one of the power switching elements, and wherein the at least one resistance arrangement is switchable between several states, and different discharge voltages for the at least one of the power switching elements are generated depending on a state of the at least one resistance arrangement.
3 . The electric circuit arrangement according to claim 2 , wherein the at least one resistance arrangement includes multiple resistors which are switchable across a resistance switching element connected in parallel with the control input of the at least one of the power switching elements.
4 . The electric circuit arrangement according to claim 2 , wherein the at least one resistance arrangement forms, with at least one further resistance, a voltage divider, and a power supply voltage generated by a voltage source drops across the voltage divider.
5 . The electric circuit arrangement according to claim 4 , wherein the power supply voltage generated by the voltage source is also a power supply voltage of the driver circuits, or the voltage source is separate from a voltage source of the driver circuits.
6 . The electric circuit arrangement according to claim 1 , wherein the discharge information includes at least one discharge current measured value describing the discharge current of the at least one energy accumulator that is being discharged or at least one voltage metering value describing a voltage of the energy accumulator which is being discharged.
7 . The electric circuit arrangement according to claim 1 , wherein the discharge control device, in a short circuit discharge operation, generates the discharge voltage of a first one of the power switching elements and the discharge control circuit, in operation, switches a second one of the power switching elements to a fully closed state.
8 . The electric circuit arrangement according to claim 7 , wherein the discharge control device, in operation, selects and carries out the short circuit discharge operation or the freewheel discharge operation at a start of the discharge operation based on machine type information that describes a machine type of an electric machine that is connectable to the electric circuit arrangement.
9 . The electric circuit arrangement according to claim 8 , wherein the machine type information is stored in the discharge control device.
10 . The electric circuit arrangement according to claim 1 , wherein the at least one energy accumulator is a capacitor.
11 . The electric circuit arrangement according to claim 10 , wherein the electric circuit arrangement is configured as multi-phase inverter.
12 . The electric circuit arrangement according to claim 1 , wherein the electric circuit arrangement is included in an electric drive device and is connected to an electric machine.
13 . The electric circuit arrangement according to claim 12 , wherein the electric circuit arrangement is included in a motor vehicle.
14 . The electric circuit arrangement according to claim 1 , wherein the electric circuit arrangement is included in an electric drive device.
15 . A method of operating an electric circuit arrangement including at least one half bridge having two power switching elements and two driver circuits, and a discharge control circuit that is different from the two driver circuits, wherein the half bridge is connectable in parallel with at least one energy accumulator and each power switching element of the power switching elements has a switchable section with an electric resistance that is adjustable by a control voltage at a control input of the power switching element, the method comprising: while in a normal operation of the power switching elements, generating, by the driver circuits, the control voltage at the control input of each of the power switching elements; and in at least one discharge operation that discharges the at least one energy accumulator, generating, by the discharge control circuit, a discharge voltage based on a discharge current of the at least one energy accumulator that is being discharged as the control voltage at the control input of at least one of the power switching elements, the discharge voltage placing the at least one of the power switching elements in linear operation, wherein the discharge control circuit comprises at least one discharge control device that, in operation, sets an amplitude of the discharge voltage based on discharge information, wherein the discharge control circuit, in operation, generates discharge voltages of both of the power switching elements, and the discharge control device, in operation, sets, in a freewheel discharge operation, the discharge voltages based on discharge information including two voltage metering values describing respectively a voltage drop across each of the power switching elements, and wherein the voltage drop across a first one of the power switching elements is equal to the voltage drop across a second one of the power switching elements.

Description

BACKGROUND Technical Field The disclosure relates to an electric circuit arrangement, comprising at least one half bridge composed of two power switching elements and two driver circuits, wherein the half bridge is or can be hooked up in parallel with at least one energy accumulator and the power switching elements each have a switchable section, the electric resistance of which can be adjusted by a control voltage of the power switching element which is imposed at a control input of the power switching element, while in a normal operation of the power switching elements the control voltage can be generated each time across a driver circuit of the power switching element. In addition, the disclosure relates to an electric drive device, a motor vehicle and a method for operating an electric circuit arrangement. Description of the Related Art In the field of electrification of vehicles, especially electromobility, electric machines, usually rotary-field electric machines, are used as drive devices for vehicles, such as motor vehicles like electric motor vehicles or hybrid motor vehicles. For example, permanently excited synchronous machines, externally excited synchronous machines and/or asynchronous machines can be used. In the corresponding drive device, the electric circuit arrangement used is typically an inverter, especially a multiphase inverter, which can actuate the electric machine. The inverter can be understood as being a connecting link between the DC voltage side, represented especially by a high-voltage battery, and the alternating current side, represented especially by the electric machine. One component of such inverters is usually also an energy accumulator, which can support the DC voltage on the inverter and which is designed for example as an intermediate circuit capacitor. In this way, the intermediate circuit capacitor can also perform the additional task of filtering signals on the high voltage, direct current side of the inverter. For safety reasons, the voltage of the intermediate circuit capacitor or an energy accumulator in general must be discharged upon ending an operational phase, such as the switching off of the motor vehicle, and/or in critical situations (active discharging). Due to the large capacitance of such energy accumulators and the high voltage, high electric energy may be present, so that dedicated discharge circuits or their discharge elements, especially discharge resistors, may be large and expensive. For example, it has been proposed to actively discharge the energy accumulator across a discharge resistance and a semiconductor switch. This involves both high costs and a significant consumption of design space. Furthermore, the discharge resistances themselves and any other nearby components become heavily heated. Electric Circuit arrangements such as the mentioned inverters moreover also usually comprise at least one half bridge on the alternating current side, especially a number of half bridges corresponding to the number of phases. Half bridges usually have power switching elements, such as IGBTs and/or MOSFETs, which can be switched between an open and a closed state by way of an associated driver circuit, by applying a corresponding control voltage at a control input (gate input). However, the power switching elements, which are usually designed as semiconductor switches, as mentioned, can also only be operated basically in a so-called linear region, in which a resistance can be set by the control voltage at the control input. It has already been proposed in the prior art to use this linear region for desired discharge processes during the normal operation. In this regard, DE 10 2014 202 717 B3 discloses a system with a control regulator, an inverter, an intermediate circuit capacitor, which is coupled to input terminals of the inverter, at least one temperature sensor, which is designed to determine a temperature change of the semiconductor switches of the half bridge of the inverter, and a voltage sensor, which is designed to determine the voltage on the intermediate circuit capacitor. The control device is designed to trigger the semiconductor switches based on a control signal of the control regulator. The control signal is generated as a series of control signal pulses with an adjustable pulse length, so that the semiconductor switches of the half bridge of the inverter are not fully conductive during the pulse length upon actuation by the control signal, so that a current capacitance of the intermediate circuit capacitor can be calculated based on a detected temperature change of the temperature sensor and a detected voltage change of the voltage sensor during the actuating of the semiconductor switches. DE 10 2017 121 579 A1 relates to an active discharge circuit for an intermediate circuit capacitor making use of phase branch switches, where a discharging can occur in a drive system for an electric motor vehicle by using only local measures within an