RU2641098C1 - Solid-state contactor for batteries - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: solid-state contactor for batteries comprises a switching unit of the battery and charger, consisting of a group of paralleled power field transistors, series-opposite connected second group of paralleled power field transistors, a transistor connection circuit with galvanic isolation, and the switching unit of the battery and load connected to it, consisting of paralleled power field transistors and transistor connection circuit with galvanic isolation.

EFFECT: providing switching of the load, charger and battery, complete limitation of the reverse current flow, galvanic isolation of control signals from the battery management system which increases the safety of the device operation and significantly increases the nominal value of the current.

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Description

FIELD OF THE INVENTION

The invention relates to electronic equipment, namely, switching devices in rechargeable batteries, including traction lithium batteries.

State of the art

The most common switching devices in batteries (battery) are electromechanical contactors. However, solid-state contactors, unlike electromechanical ones, have a large switching resource and lower cost.

Solutions from Littlefuse (http://www.littelfuse.com/products/dc-solenoids-and-relays/solid-state-relays.aspx), Teledyne Relays (http://www.teledynerelays.com/pdf/military/ m33-2n.pdf), Crydom (http://www.crydom.com/en/products) are solid state relays that switch using power transistors and are designed for currents up to 100 A. These solid state relays are general purpose relays , the circuitry of these solutions is not optimized for use in rechargeable batteries, for switching the battery of the charger and load, when using known solutions, two full-fledged solid-state relays are required, and edpolagayut work only up to 100 A, and does not provide complete protection against reverse current flow.

Disclosure of invention

The technical task is to develop a solid-state contactor device designed to switch the load and the charger with the function of protection against reverse current flow.

The technical result consists in providing switching of the load, charger and battery, in completely limiting the flow of reverse current, providing galvanic isolation of control signals from the control system of the battery, increasing the conducted current.

The technical result is achieved due to the fact that the solid-state contactor for batteries contains a switching unit for the battery and charger, consisting of a group of parallel-connected power field-effect transistors, a counter-connected series of a second group of parallel-connected power field-effect transistors, a connection circuit for transistors with galvanic isolation, and the associated battery and load switching unit, consisting of a group of parallel connected power fields transistors and switching transistors with galvanic isolation.

Brief Description of the Drawings

The figure shows a diagram of a solid state contactor.

The implementation of the invention

The solid-state contactor is designed for switching the battery, charger and load. Switching in a solid-state contactor is carried out using semiconductor switches (MOSFET power field-effect MOSFETs) with a rated operating voltage sufficient to operate with a specific battery (specific voltage).

The solid-state contactor for the battery, including for lithium traction batteries, consists of a battery switching unit and a charger, which consists of a group of parallel-connected power field-effect transistors 1 (MOS transistors - MOSFETs), and another group of parallel-connected power transformers is connected in series field-effect transistors 2, switching circuits for galvanic isolated transistors 3, and a battery and load switching unit, which consists of a group included power field-effect transistors 5 and switching transistors with galvanic isolation 4.

The switching units are interconnected via the positive power bus of the battery 6. The switching circuits for transistors with galvanic isolation 3 and 4 are connected to an external battery management system (BMS - Battery Management System). The switching unit of the battery and charger is connected through the power connector to the charger and through the power bus 6 to the battery. The battery and load commutation unit is connected through the power connector to the electric drive and through the power bus 6 to the battery.

In the absence of a permissive signal from the battery control system to the transistor 3 switching circuit, connecting a load or a voltage source with a voltage level lower than the battery voltage to the charger connector, the transistor group 2 on-board does not allow current to flow from the battery to the charger connector.

Power field-effect transistors have a parasitic reverse diode in their structure, which, when the transistor is off, allows discharge through the charging connector and charge through the discharge connector. During the operation of the battery, there are cases of erroneous connection of the load to the charge connector, in addition, some types of chargers in the off state can be a load in relation to the battery. The flow of reverse current is accompanied by increased losses on the reverse diode and the rapid failure of the transistor. In addition, for safety reasons, the charge connector must not be live. To prevent reverse current through the charge connector, the on-board switching on of power field-effect transistors 1, 2 is used. For the discharge connector, the on-board switching on of power field-effect transistors is not required, since in the practical use of the battery, the discharge connector is switched once during installation in the system, and the charging connector is switched regularly.

To increase the rated current of the contactor and reduce the resistance of the transistor in the open state, parallel connection of transistors is used. Due to the positive temperature coefficient of power MOS transistors, currents are aligned between transistors connected in parallel.

The solid-state contactor is galvanically isolated between the transistor driver and the control signal to ensure isolation of the control circuits and power circuits.

Due to the implementation of the claimed device in the above manner, switching of the load, the charger and the battery, a complete limitation of the reverse current flow, galvanic isolation of control signals from the control system of the battery, an increase in the conducted current, with the possibility of conducting current up to 350 A in nominal and up to 1000 A at the peak.

Claims (1)

     A solid-state contactor for batteries, characterized in that it contains a switching unit for the battery and charger, consisting of a group of parallel-connected power field-effect transistors, a counter-connected second group of parallel-connected power field-effect transistors, and a galvanic isolated transistor switching circuit battery and load switching unit, consisting of a group of parallel-connected power field-effect transistors and circuits Isolated transistors.

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