DE102022119740A1 - Control of a DC converter for DC charging - Google Patents

Abstract

An electrical system may include a rechargeable energy storage system (RESS) and a direct current to direct current (DC-DC) converter. The DC-to-DC converter is connected to the RESS and configured to be connected to a DC charging station. The DC-to-DC converter is configured to selectively connect the RESS to the DC charging station such that charging current is selectively supplied to the RESS during a charging operation.

Description

technical field

The present disclosure relates to an electrical system that enables charging of batteries from a DC charger functioning as a power source via a DC-to-DC converter.

introduction

Direct current to direct current (DC-DC) converters convert a direct current source from one voltage level to another voltage level. For example, switched DC-to-DC converters can convert one DC voltage level to another by temporarily storing the input energy and then releasing the stored energy to the output at a different voltage.

Description of the invention

An example of an electrical system that boosts a voltage provided by a direct current (DC) charging station is disclosed. The electrical system may include a Rechargeable Energy Storage System (RESS) and a DC-to-DC (DC-DC) converter. The DC-to-DC converter is connected to the RESS and configured to connect to a DC charging station. The DC-to-DC converter is configured to selectively connect the RESS to the DC charging station such that charging current is selectively provided to the RESS during a charging operation.

In other features, the DC-DC converter includes a first switch and a second switch.

In other features, the first switch and the second switch comprise a voltage-controlled semiconductor switch.

In other features, the semiconductor voltage-controlled switch comprises at least one of a silicon insulated gate bipolar transistor (silicon IGBT), a silicon carbide metal oxide semiconductor field effect transistor (silicon carbide MOSFET), a silicon superjunction MOSFET, a gallium nitride field effect transistor (GaN-FET), a SiC Junction Field Effect Transistor (SiC-JFET), a wide bandgap (WBG) device, and an ultra wide bandgap (UWBG) device.

In other features, the first switch and the second switch are configured to operate in complementary operating states.

In other features, the electrical system includes a controller operatively connected to the DC-DC converter and configured to operate the DC-DC converter to switch the RESS based on a gate signal applied to the first switch and/or the second switch is provided to selectively connect to the DC charging station.

In other features, the controller is further configured to compare an input DC-DC converter voltage to a predetermined voltage threshold and selectively operate the first switch to ramp up a voltage stored by a pre-charge capacitor, the pre-charge capacitor using RESS provided energy is charged.

An example of an electrical system that boosts a voltage provided by a DC charging station is disclosed. The electrical system may include a rechargeable energy storage system (RESS) and a direct current-to-direct current (DC-DC) converter. The DC-DC converter is connected to the RESS and configured to connect to a DC charging station. The DC-DC converter is configured to selectively connect the RESS to the DC charging station such that charging current is selectively supplied to the RESS during a charging operation.

In other features, the DC-DC converter includes a first switch and a second switch.

In other features, the first switch and the second switch comprise a voltage-controlled semiconductor switch.

In other features, the semiconductor voltage-controlled switch comprises at least one of a silicon insulated gate bipolar transistor (silicon IGBT), a silicon carbide metal oxide semiconductor field effect transistor (silicon carbide MOSFET), a silicon superjunction MOSFET, a gallium nitride field effect transistor (GaN-FET), a SiC Junction Field Effect Transistor (SiC-JFET), a wide bandgap (WBG) device, and an ultra wide bandgap (UWBG) device.

In other features, the first switch and the second switch are configured to operate in complementary operating states.

In other features, the electrical system includes a controller operatively connected to the DC-DC converter and configured to operate the DC-DC converter to switch the RESS based on a gate signal applied to the first switch and/or the second switch is provided to selectively connect to the DC charging station.

In other features, the controller is further configured to compare an input DC-DC converter voltage to a predetermined voltage threshold and selectively actuate the first switch to ramp up a voltage stored by a pre-charge capacitor, wherein the pre-charge capacitor is charged using RESS provided energy is charged.

A method is disclosed that includes comparing an input DC-DC converter (DC-DC) voltage of a DC-DC converter to a predetermined voltage threshold and selectively operating a first switch of the DC-DC converter to ramp up a voltage stored by a pre-charge capacitor, wherein the pre-charge capacitor is charged using energy provided by a rechargeable energy storage system (RESS). The method also includes selectively operating a second switch of the DC-DC converter to ramp up a charge current to a predetermined charge current threshold such that the charge current recharges the RESS.

In other features, the charging current is provided by a DC charging station.

In other features, the DC charging station includes a DC fast charging station capable of output from about fifty kilowatts (50 kW) to about three hundred and fifty kilowatts (350 kW).

In other features, the first switch and the second switch comprise a voltage-controlled semiconductor switch.

In other features, the semiconductor voltage-controlled switch comprises at least one of a silicon insulated gate bipolar transistor (silicon IGBT), a silicon carbide metal oxide semiconductor field effect transistor (silicon carbide MOSFET), a silicon superjunction MOSFET, a gallium nitride field effect transistor (GaN-FET), a SiC Junction Field Effect Transistor (SiC-JFET), a wide bandgap (WBG) device, and an ultra wide bandgap (UWBG) device.

In other features, the first switch and the second switch are configured to operate in complementary operating states.

Further areas of application will emerge from the present description. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

character list

• 1 ist eine schematische Darstellung eines Beispiel-Kraftfahrzeugs, das an eine externe Gleichstrom-Ladestation angeschlossen ist;
• 2 ist ein Blockdiagramm einer beispielhaften Gleichstrom-Ladeschaltung, d.h. eines elektrischen Systems, gemäß einer beispielhaften Implementierung;
• 3 ist ein Schaltplan des Beispiels eines elektrischen Systems gemäß einer Beispielimplementierung; und
• 4 ist ein Flussdiagramm, das einen beispielhaften Prozess zum Aufladen eines RESS eines Fahrzeugs über eine externe Stromquelle gemäß einer beispielhaften Implementierung zeigt.

The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way.

• 1 Figure 12 is a schematic representation of an example motor vehicle connected to an external DC charging station;
• 2 12 is a block diagram of an example DC charging circuit, ie, an electrical system, according to an example implementation;
• 3 Figure 12 is a circuit diagram of an example electrical system according to an example implementation; and
• 4 12 is a flow chart depicting an example process for charging a RESS of a vehicle via an external power source, according to an example implementation.

Detailed description

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or use.

1 shows an example of a direct current charging circuit 10 (DC charging circuit 10) as part of a motor vehicle 20. The vehicle 20 is shown in a direct current fast charging process in which the direct current charging circuit 10 is electrically connected via a charging connection 11 and a charging cable 15 to a external DC charging station 30, eg, using an SAE J1772 charging plug or other suitable regional or national standard charging plug or connector. The present disclosure is independent of the particular charging standard that will ultimately be used in a DC fast charge gear is used with the DC charging station 30 and therefore the above examples are merely illustrative. For example, the DC charging station 30 may be a DC fast charging station capable of powering the vehicle 20 with an output of between about fifty kilowatts (50 kW) and about three hundred and fifty kilowatts (350 kW). lies. In another possible embodiment, the vehicle 20 could be charged by a second vehicle capable of providing the vehicle 20 with charging energy.

The DC charging circuit 10 can be used as part of the motor vehicle 20 as well as other electrical systems such as stationary or mobile power plant robots or platforms. In vehicular applications, non-automotive vehicles such as airplanes, watercraft, and rail vehicles can also benefit from similar benefits. The DC charging circuit 10 may be used as part of a powertrain of a mobile system such as the example vehicle 20 . For purposes of illustration, an application of the DC charging circuit 10 as an integral part of the vehicle 20 in an automotive context is described below, without limiting the present disclosure to such an implementation.

The vehicle 20 from 1 includes a body 12 and drive wheels 14. The body 12 may define or contain the charge port 11 in a user accessible location. The vehicle 20 can be embodied in various ways as a plug-in electric vehicle with an on-board rechargeable energy storage system (RESS) 120, as shown in FIGS 2 and 3 1 and described below, for example, with a multi-cell lithium-ion, zinc-air, nickel-metal hydride, or lead-acid DC battery pack selectively charged using the external DC charging station 30 of FIG 1 can be recharged. During operation of the vehicle 20, the RESS 120 may provide electrical energy to one or more powertrain/traction components of the vehicle 20, such as an electric machine (EM), eg, a traction motor, to generate and transmit motor torque to the drive wheels 14 to propel the vehicle 20 or to perform other useful work on board the vehicle 20.

2 1 shows a block diagram of a DC charging circuit 10 for the vehicle 20 according to various implementations. As shown, the DC charging circuit 10 includes a controller 105, which may include at least a processor and memory for storing computer-readable instructions. The memory includes tangible, non-volatile memory, eg, read-only memory, whether optical, magnetic, flash, or otherwise. The controller 105 also includes sufficient amounts of random access memory (RAM), electrically erasable programmable read only memory, and the like, as well as a high-speed clock, analog-to-digital and digital-to-analog circuitry, and input/output circuitry and devices, as well as appropriate signal conditioning and buffer circuits.

The DC charging circuit 10 also includes a gate driver 110 and a direct current to direct current (DC-DC) converter 115. The controller 105 is operatively connected to the gate driver 110 and the DC-DC converter 115. FIG. Based on the control signals output from the controller 105, the gate driver 110 controls one or more switches within the DC-DC converter 115, as referred to below with respect to FIG 3 explained in more detail. In various implementations, controller 105 may include a pulse width modulator that provides pulse width modulated signals to gate driver 110 . The gate driver 110 can operate the DC-DC converter 115 based on the signals received from the pulse width modulator.

As illustrated, the DC charging circuit 10 also includes an onboard rechargeable energy storage system (RESS) 120 configured to store high voltage electrical energy used to propel an electrified vehicle, such as the vehicle 20 of FIG 1 .

The RESS 120 may be a high amperage deep cycle battery system rated for about four hundred (400) to about eight hundred (800) volts direct current (VDC) or more, depending, for example, on desired vehicle range, the total weight of the vehicle; and the power levels of the various consumers drawing electrical power from the RESS 120 in various implementations. However, it is understood that the RESS 120 can also be designed for other voltages. The RESS 120 may include one or more independently rechargeable high voltage battery packs.

When the DC charging station 30 is connected to the vehicle 20, e.g. the charging cable 15 of the DC charging station 30 is connected to the charging port 11 of the vehicle 20, the DC charging station 30 supplies electric power to the DC-DC converter 115 in order to charge the RESS 120.

3 12 shows a schematic diagram of the DC charging circuit 10 according to an embodiment of the present disclosure. As illustrated, the DC-DC converter 115 may include a first switch 205 and a second switch 210 . In an example implementation, switches 205, 210 comprise voltage-controlled semiconductor switches that are controlled by control signals provided by controller 105 via gate driver 110. In various implementations, the switches 205, 210 comprise a voltage controlled switching device in the form of a silicon insulated gate bipolar transistor (silicon IGBT), a silicon carbide (SiC) metal oxide semiconductor field effect transistor (silicon carbide MOSFET), a silicon Superjunction MOSFET, a gallium nitride field effect transistor (GaN-FET), a SiC junction field effect transistor (SiC-JFET), another wide bandgap (WBG) device or ultra-wide bandgap (UWBG) semiconductor power switching device, or another suitable switch with a corresponding gate to which a gate signal is applied to change the on/off state of a particular switch.

As in 3 As shown, the gate driver 110 is operatively connected to the gates 215, 220 of the switches 205, 210 and provides gate signals to the respective gates to control whether the respective switch 205, 210 operates in an open state to allow current flow prevent, or in a closed state to allow current flow. Gate driver 110 may include an inverter 225 that inverts the gate signal provided by gate driver 110 . For example, an output 230 of the gate driver 110 is connected to the gate 220 of the second switch 210 and an output 235 of the inverter 225 is connected to the gate 215 of the switch 205 . Based on this configuration, the switches 205, 210 operate in a complementary state in which when one of the switches 205, 210 is in the closed state, the other of the switches 205, 210 operates in the open state.

The DC charging circuit 10 may also include a pre-charge capacitor 230 and a discharge resistor 235 connected in parallel. The pre-charge capacitor 230 and the discharge resistor 235 are connected between the positive terminal 240 and the negative terminal 245 .

DC charging circuit 10 also includes an inductor 250 between node 255 and node 260. Node 255 includes an electrical node to which the positive terminals of pre-charge capacitor 230 and discharge resistor 235 are connected. Node 260 includes an electrical node that can serve as an input to switches 205,210. Depending on the operation of the DC charging circuit 10, electrical energy can be routed via the inductance 250 to one of the switches 205, 210, for example. The DC charging circuit 10 may also include an output capacitor 265 . Precharge capacitor 230, discharge resistor 235, inductor 250, and output capacitor 265 may have any suitable values consistent with the present disclosure.

When the DC charging station 30 is connected to the DC charging circuit 10, the DC charging station 30 acts as a power source for the DC-DC converter 115. As described in more detail herein, a boost mode technique can be used to provide the RESS 120 supply sufficient electrical energy for charging purposes. For example, the boost mode technique can be used to account for an internal resistance 270 and an internal inductance 275 associated with the RESS 120 .

4 FIG. 4 is a flow diagram of an example method 400 for selectively charging the RESS 120 from an external power source, such as the DC charging station 30, acting as a power source whose maximum voltage is lower than that of the RESS 120. The blocks of the method 400 may derive from FIG control 105 are executed. The method 400 begins at block 402. At block 405, a vehicle charge command is received at the controller 105. FIG. For example, the vehicle charge command may be provided to the controller 105 when a plug of the charge cable 15 is connected to the charge port 11 .

In block 410, it is determined whether an input DC-DC converter voltage is greater than or equal to a predetermined voltage threshold. The controller 105 may determine whether the input DC-DC converter voltage is greater than or equal to the predetermined voltage threshold using one or more sensors (not shown) employed in the DC charging circuit 10 . The one or more sensors can be voltage sensors, for example, which determine a voltage value at one or more nodes within the DC charging circuit 10 . In some embodiments, the input DC-DC converter voltage may include the voltage stored by the pre-charge capacitor 230 .

If the input DC-DC converter voltage is below the predetermined voltage threshold, in block 415 the controller 105 causes the gate driver 110 to generate control signals genes that control the operation of the switch 205. For example, gate driver 110 may transmit control signals such that a buck mode duty cycle is applied to gate 215, thereby operating DC-DC converter 115 in a buck mode that causes the voltage stored on pre-charge capacitor 230 to drop to the predetermined Voltage threshold increases. During the buck mode of operation, the pre-charge capacitor 230 is charged to the predetermined voltage threshold via the energy provided by the RESS 120 .

If the input DC-DC converter voltage is greater than or equal to the predetermined voltage threshold, in block 420 the controller 105 causes the gate driver 110 to output control signals to the switches 205, 210 according to a boost mode duty cycle to achieve a Charging current ramp up to a predetermined charging current threshold. In an example implementation, the predetermined charging current threshold may be approximately one hundred twenty-five amperes (125 A). However, it should be understood that other predetermined charging current thresholds may be selected based on a charging event. In various implementations, switch 210 (as well as switch 205 due to the complementary nature of switches 205, 210) of DC-DC converter 115 is controlled via the control signals applied to gate 220 to control a charging current supplied to RESS 120 becomes. The boost mode duty cycle may control an amplitude of the charge current such that the charge current increases up to the predetermined charge current threshold. The charging current can be supplied from the DC charging station 30 to the RESS 120 via the switch 205 . In some cases, the controller 105 causes the gate driver 110 to output control signals with a dead time between the complementary signals applied to the gates of 215 and 220 to mitigate the current shoot-through through the switches 205 and 210.

Block 425 determines whether loading is complete. For example, the controller 105 may compare a voltage stored by the RESS 120 to a RESS voltage threshold. When the voltage stored by the RESS 120 is greater than or equal to the RESS voltage threshold, charging is complete. If the loading process is not complete, the method 400 returns to block 420 .

Otherwise, controller 105 causes the charge current to ramp down by placing switch 210 in the open state at block 430 . In block 435 the controller 105 causes both switches 205, 210 to transition to the open state and the voltage stored in the pre-charge capacitor 230 is discharged through the discharge resistor 235. The method 400 then ends in block 440.

The description of the present disclosure is merely exemplary in nature and variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the present disclosure.

Claims (7)

An electrical system that boosts voltage supplied by a DC charging station, comprising: a rechargeable energy storage system, RESS; and a DC-to-DC converter, DC-DC converter connected to the RESS and configured to connect to the DC charging station, wherein the DC-DC converter is configured to selectively connect the RESS to the DC charging station to connect so that the RESS is selectively provided with a charging current during a charging process. The electrical system after claim 1 , wherein the DC-DC converter comprises a first switch and a second switch. The electrical system after claim 2 , wherein the first switch and the second switch comprise a voltage-controlled semiconductor switch. The electrical system after claim 3 , wherein the voltage-controlled semiconductor switch is at least one of a silicon-insulated-gate bipolar transistor, silicon IGBT, a silicon carbide-metal-oxide-semiconductor field effect transistor, silicon carbide MOSFET, a silicon superjunction MOSFET, a gallium nitride field effect transistor, GaN-FET , a SiC junction field effect transistor, SiC-JFET, a wide bandgap, WBG device, and an ultra wide bandgap, UWBG device. The electrical system after claim 2 , wherein the first switch and the second switch are configured to operate in complementary operating states. The electrical system after claim 2 , further comprising: a controller operatively connected to the DC-DC converter and configured to control the DC-DC operate converters to selectively connect the RESS to the DC charging station based on a gate signal provided to the first switch and/or the second switch. The electrical system after claim 6 , wherein the controller is further configured to: compare an input DC-DC converter voltage to a predetermined voltage threshold; and selectively operate the first switch to ramp up a voltage stored by a pre-charge capacitor, the pre-charge capacitor being charged using energy provided by the RESS.

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