DE102020124596A1 - Method and circuit for setting small currents in a battery quick charge - Google Patents

Abstract

The invention relates to a method for setting small currents in a battery quick charge, in which a semiconductor module has a circuit (100) with a high-side semiconductor switch (110) and a low-side capacitance (250), in which at a A high-voltage DC voltage is applied to the input (101, 102) of the circuit, with a coil (130) being arranged after an upper output of the circuit located between the high-side semiconductor switch and the low-side capacitance, and thus an upper output (103) of the semiconductor module is formed, in which a lower output (104) of the semiconductor module is formed by a lower output of the circuit, in which the upper output (103) and the lower output (104) of the semiconductor module are connected to two poles of a battery are formed by the coil (130) together with the low-side capacitance (250) an oscillating circuit with an oscillating circuit frequency, wherein by means of a control of the high-side semiconductor switching it (110) is operated against the oscillating circuit in that the high-side semiconductor switch (110) is switched on, adapted to the oscillating circuit frequency, during a falling coil current and a current value minimum is thereby defined, and the high-side semiconductor switch is switched off during a rising coil current and thereby switched on current value maximum is defined.

Description

The present invention relates to a method for setting small currents using an oscillating circuit when charging electric vehicles quickly. Furthermore, a circuit is claimed on which the method is implemented.

Today's electric vehicles generally allow two charging modes. For charging at a standard AC or three-phase socket, a vehicle has an on-board charger that both performs the necessary conversion to direct current and controls the charging operation. However, this AC charging mode is extremely limited in charging speed due to the available connection power (usually no more than 16 A or 32 A) and due to the installation of the charger with sufficient power. With today's electric vehicles, this results in charging times of hours up to several hours per 100 km.

Due to such high AC charging times, charging with DC voltage was developed as a second charging mode. The vehicle does not have its own charger. Instead, a vehicle-external charging station carries out the charging process and influences the voltage and current in order to coordinate a charging process with a battery. During the charging process, the DC charging cables are usually connected directly to the poles of the vehicle's high-voltage battery; In a few cases, there are also other converting power electronics in the vehicle between the charging connection and the battery, for example DC step-up converters to increase or decrease the voltage for the battery, as for example in the publication DE 10 2017 123 348 A1 described. There is usually no galvanic isolation between the DC charging lines and the battery. The power of DC charging stations is currently up to 50 kW, but the first charging stations with 350 kW are also known. In general, by increasing the charging power and/or the charging voltage, charging times should ultimately be achieved which are in the range of a refueling process in a vehicle with an internal combustion engine.

However, not all road traffic locations have energy networks and energy connection capacities that would allow one or more vehicles to be charged with the high charging capacity, which should be 320 kW per vehicle, for example, and thus exceed typical house connection capacities many times over. This motivates the use of electrical storage devices, which can be charged slowly with the maximum power available from the supply network, but which can briefly charge one or more vehicles at the same time or one after the other with high power. For this purpose, charging stations are used in whose power electronics switches made of semiconductors are installed, e.g. silicon carbide-metal-oxide-semiconductor field effect transistors (SiC-MOSFETs) or bipolar transistors with insulated gate electrodes (IGBTs). Their regulation and control represent the lowest level of current conversion.

In order to accelerate the charging process, vehicles will be developed in the future that can be charged with ever larger direct currents in the range from 0.5 to 1 kA. Nevertheless, normative requirements for current accuracy for small currents remain, e.g. B. when the battery is finally fully charged with direct currents below 5 A up to 500 mA with accuracies of up to 150 mA. However, it is becoming increasingly difficult to provide the desired small currents at the end of the charging process using semiconductors and control methods that primarily allow large currents. This problem lies not only in the control and regulation of the semiconductors, but also partly in current sensors that must be able to measure accurately over the entire current range.

The American pamphlet US 2012/0223575 A1 discloses a device and a method for increasing charging efficiency without restricting operation of a low-voltage load in the vehicle electrical system during a normal charging process. For this purpose, two operating modes are switched, for which a half-bridge with MOSFET switches is also shown.

In the pamphlet DE 10 2019 102 998 A1 discloses a boost mode for further charging a battery connected to a DC charging station via an inverter, which is switched to as soon as the battery voltage exceeds the charging voltage. In boost mode, the charging voltage is increased by the inverter.

The pamphlet U.S. 2018/0361861 A1 describes a power supply device with a plurality of MOSFET half-bridges for rapid charging, which comprises two circuits, each with a capacitor, the two capacitors having different charging voltages. There is a voltage converter between the two circuits.

Against this background, it is an object of the present invention to present a method for rapid charging of an electric vehicle battery, in which power electronics with semiconductors designed for currents in the kA range can also provide very small currents below 5 A down to a hundred times the milliampere range. Further a circuit is to be provided with which this method can be executed or is executed.

In order to solve the above-mentioned problem, a method is proposed for setting small currents for rapid battery charging, in which a semiconductor module has a circuit with a high-side semiconductor switch and a low-side capacitance. A high-voltage direct current is applied as an input voltage to an input of the circuit. After an upper output of the circuit located between the high-side semiconductor switch and the low-side capacitance, a coil is arranged and thus an upper output of the semiconductor module is formed. A lower output of the semiconductor module is formed by a lower output of the circuit. The output of the semiconductor module formed by the lower output and the upper output is connected to two poles, i.e. the plus and minus pole of a battery. An oscillating circuit with an oscillating circuit frequency is formed by the coil together with the low-side capacitance. The high-side semiconductor switch is operated against the oscillating circuit by means of a controller, in that the high-side semiconductor switch is switched on in a manner adapted to the oscillating circuit frequency during a falling coil current, the coil current then increases and a current value minimum is thereby defined, and the high-side semiconductor switch is switched off during a rising coil current, the coil current then falls and a current value maximum is defined as a result. An output current of the semiconductor module is regulated by selecting a respective switch-on and switch-off time of the high-side semiconductor switch.

In one embodiment of the method according to the invention, the high-side semiconductor switch is switched on when the oscillating circuit has the smallest negative current value and is switched off when the oscillating circuit has a maximum positive current value. This results in an average current value over time of 0 A. The method according to the invention makes it possible to regulate currents with very small current values.

In another embodiment of the method according to the invention, the low-side capacitance is formed by a capacitor.

In yet another embodiment of the method according to the invention, the low-side capacitance is formed by a low-side semiconductor switch. In this case, the low-side semiconductor switch is in an open state, so that the low-side capacitance is a junction capacitance of the low-side semiconductor switch. This junction capacitance of the low-side semiconductor switch, often also referred to as the output capacitance Coss of the low-side semiconductor switch, can be formed in the semiconductor, for example, by a reverse-biased PN junction and/or a depleted channel of a field effect transistor. Furthermore, this depletion layer capacitance can be formed in such a way that it has a voltage dependency, for example it decreases with increasing voltage or increases with decreasing voltage. For example, the low-side capacitance can be shaped so that it is at least ten times the value at 200 V at 0 V; preferably at 0V it may be at least fifty times the value at 200V. The increase in capacitance is particularly preferred when it is mostly in the range around 0 V, for example more than 75% of the increase in capacitance takes place between 25 V and 0 V. An increase in capacitance with decreasing voltage increases the electrical charge available should the tank circuit of the low-side capacitance, the inductance and any other elements drive the voltage across the low-side capacitance close to 0V. The effective oscillating circuit frequency decreases accordingly in the case of high amplitude and/or long switching cycles, without the voltage necessarily reaching or falling below 0 V and thus an optionally present freewheeling diode beginning to conduct.

The high-side semiconductor switch and the low-side semiconductor switch are, for example, power semiconductor switches, such as N-channel MOSFETs or IGBTs. The high-voltage direct current can have voltage values in the range between 800 V and 1200 V, for example. Small currents provided by the method according to the invention have current values in a range of a few amperes, for example in a range from 5 A to 500 mA and within a tolerance range of up to 150 mA.

The method according to the invention is not based on operating a high-side semiconductor switch against a low-side transistor, as is the case with a so-called step-down converter, but according to the invention the high-side semiconductor switch against to operate an oscillator or the oscillating circuit consisting of the coil and the low-side capacitance of the semiconductor module. The low-side semiconductor switch of the half-bridge is open, so that in terms of circuitry it only appears with its intrinsic freewheeling diode. If the control of the high-side semiconductor switch prevents the coil current from becoming negative, this freewheeling diode only has a blocking effect. In this case, the method according to the invention can also be carried out without arranging the low-side semiconductor switch.

The technical implementation of the method according to the invention makes advantageous use of electrical properties of the semiconductor module, here in particular the half-bridge. The half-bridge usually assumes two states, which apply either the input voltage, e.g. from a DC link, or 0 V to the output. By means of switching modulation, e.g. pulse width modulation (PWM) or pulse amplitude modulation (PAM), any intermediate voltage between 0 V and the input voltage can be generated on average over time. In addition to the half-bridge, the semiconductor module can also have further electronic components.

The semiconductor module named in the method according to the invention has a low-side capacitance that belongs to it or is intrinsic and is mostly parasitic. While this low-side capacitance is generally undesirable in other applications, it is advantageously used in the method according to the invention to form the resonant circuit. If, in addition to the permanently open low-side semiconductor switch, the high-side semiconductor switch is also open, i.e. no current flows through either of the two semiconductor switches of the half-bridge, an oscillating circuit builds up through the coil and the low-side capacitance, which is used is used to set currents with small current values. For this purpose, the high-side semiconductor switch must be switched to match the resonant circuit frequency of the resonant circuit that is being formed.

In a further embodiment of the method according to the invention, the low-side capacitance is chosen to be sufficiently large so that the low-side capacitance fully provides a charge for a coil current during a reversal process and thus gap-free operation can be and/or is carried out. A voltage Uc,oss of the low-side capacitance should always remain positive. If it reaches 0 V, the low-side capacitance no longer feeds the current as desired, but instead, for example, the optional freewheeling diode of the low-side semiconductor switch. In this way, the behavior would once again approach a discontinuous operation (discontinuous current mode) of the step-down converter, which is undesirable here.

The method according to the invention has a number of advantages over the step-down converter known from the prior art. In the step-down converter, which operates the high-side semiconductor switch against the low-side semiconductor switch in a half-bridge, there must be a dead time between switching off one semiconductor switch and switching on the other semiconductor switch, which can be 100 ns and up to 1000 ns, for example can be introduced. A commutation time must also be taken into account in the freewheeling diode of a low-side semiconductor switch that is operated in the open state. With the step-down converter, however, the dead time must be included differently in the behavior of the step-down converter depending on the current direction or current amplitude, e.g. whether the current changes to the other semiconductor switch at the beginning of the dead time or only at the end of the dead time. This changes the behavior of a controlled system, which must be taken into account by a controller. For example, the behavior is different if a triangular coil current crosses the zero line within one cycle. Above a certain duty cycle, an on-time of one of the semiconductor switches falls below a length of the dead time. As a result, this semiconductor switch is no longer activated and the controlled system behaves differently than desired. In the buck converter, all of these circumstances mean that very small currents with a small voltage difference between the intermediate DC voltage circuit, also known as the DC intermediate circuit, and the output of the buck converter can only be set at great expense with very clever control constructs. Furthermore, in the case of switching modulation or PWM units of many microcontrollers or digital signal processors, also abbreviated to DSP, which are used to regulate and control power electronics, as well as in the case of independent PWM ICs, maximum and minimum duty cycles are limited. For example, it is often only possible to set a minimum duty cycle of 1% and a maximum duty cycle of 99%. Because of the above reasons, one would have to use high-performance charging systems with very small currents and, in particular, output voltages close to the DC intermediate circuit voltage, i. H. i.e. with very marginal duty cycles, keep and operate several different controllers with the smoothest possible transition. Each transition would depend on erroneous sensor signals and would in itself be a source of unwanted oscillations.

In yet another embodiment of the method according to the invention, a highly non-linear behavior, in which a capacitance value increases sharply at low voltage, is selected for the low-side capacitance. In this context, a highly non-linear behavior means that at a voltage value of less than 10% of a nominal voltage, the strong increase in the capacitance value has at least a factor of 2. A factor of 5 or higher is even more advantageous. For such a non-linear behavior, a discharge slows down when the voltage drops and delays the unwanted reaching of 0 V for the voltage Uc,oss.

gerade die low-side-Kapazität bei hohen Spannungswerten den Energieinhalt und somit die Schaltverluste. Im Gegensatz dazu ist für den Oszillator, der vom erfindungsgemäßen Verfahren bei kleinen Strömen genutzt wird, jedoch gerade die low-side-Kapazität bei kleinen Spannungen relevant, da für ein Kommutieren des Stromes nicht der Energieinhalt sondern die Ladung insbesondere bei kleinen Spannungswerten der low-side-Kapazität von Bedeutung ist. Bei kleinen Spannungswerten der low-side-Kapazität ist die Spannung über die Induktivität maximal negativ und treibt ein Umschwingen des Stromes.Another advantage of the strongly non-linear behavior is that switching losses are also reduced at the same time. In a normal operation of the half bridge according to the prior art, the low-side capacitance is recharged in each switching cycle by changing from the high-side semiconductor switch to the low-side semiconductor switch, and the energy released in the process is converted into losses. However, increased here due to the non-linearity of an energy content $\left(1/2C{u}_C^2\right)$

especially the low-side capacitance at high voltage values the energy content and thus the switching losses. In contrast to this, the low-side capacitance is relevant for the oscillator, which is used by the method according to the invention for small currents, for small voltages, since it is not the energy content but the charge that is important for commutation of the current, particularly for small voltage values of the low-side side capacity matters. With small voltage values of the low-side capacitance, the voltage across the inductance is negative at most and drives the current to reverse.

In a continued yet further embodiment of the method according to the invention, a low-pass filter is formed by arranging a low-pass capacitor between the terminals of the output of the semiconductor module together with the coil, as a result of which the output current has a constant time profile. Relatively smooth current and/or voltage curves are obtained as a result of the low-pass filter formed in this way at the output of the circuit. By default, low-pass filters have an inductance like the coil arranged according to the invention, which is also referred to as a choke, in order to stabilize the current that flows. Such an inductance creates an inertia for the current, since the current I can only change steadily with the driving voltage U and the inductance L according to dl/dt = U/L. A low-pass capacitor is often used to stabilize the output voltage.

The implementation of the method according to the invention requires precise component knowledge, such as, for example, the switching behavior of the semiconductor switches over time, the low-side capacitance of the semiconductor module that forms, and coil characteristics. However, this is usually stated in data sheets from manufacturers of the electronic components.

Furthermore, a circuit for setting small currents in a quick battery charge is claimed, in which a semiconductor module has a high-side semiconductor switch and a low-side capacitance. A coil is arranged downstream of an upper output of the circuit located between the high-side semiconductor switch and the low-side capacitance, and an upper output of the semiconductor module is thus formed. A lower output of the semiconductor module is formed by a lower output of the circuit. The output of the semiconductor module formed by the upper output and the lower output is connected to a battery. A high-voltage direct current is applied to an input of the circuit. The inductor is configured together with the low-side capacitance to form a tank circuit with a tank circuit frequency. A controller is configured to operate the high-side semiconductor switch against the oscillating circuit by switching on the high-side semiconductor switch during a falling coil current, adapted to the oscillating circuit frequency, and the coil current then increases, which defines a current value minimum, and it switches the high -side semiconductor switch turns off during a rising coil current and the coil current then falls, which defines a maximum current value. An output current of the semiconductor module can be regulated and/or regulated by selecting a respective switch-on and switch-off time of the high-side semiconductor switch.

Due to the inventive operation of the high-side semiconductor switch against the low-side capacitance and the formation of an oscillator together with the coil, an electrical system formed by the circuit behaves more linearly and/or linearizable than a conventional "buck converter" in the so-called " discontinuous current mode", i.e. intermittent operation.

In one embodiment of the circuit according to the invention, the low-side capacitance is chosen to be sufficiently large so that the low-side capacitance fully provides a charge for a coil current during a reversal process and thus gap-free operation can be carried out and/or takes place.

In a further refinement of the circuit according to the invention, the low-side capacitance exhibits a highly non-linear behavior in which a capacitance value increases sharply at low voltage.

In yet another embodiment of the circuit according to the invention, a low-pass filter is formed by arranging a low-pass capacitor between the terminals of the output of the semiconductor module together with the coil.

In a continued further embodiment of the circuit according to the invention, the low-side capacitance is formed by a capacitor.

In a continuously different embodiment of the circuit according to the invention, the low-side capacitance is formed by a low-side semiconductor switch.

Furthermore, a use of the circuit for setting small currents in a battery rapid charge is claimed, the semiconductor module being an inverter with a plurality of half-bridges and being configured with a circuit according to the invention, and a method according to the invention being carried out. Such an inverter can be formed, for example, by a semiconductor module of a modular multilevel converter, as is the case, for example, with a modular multilevel converter with serial and parallel connectivity, also abbreviated as MMSPC. Such a modular multilevel converter system is described, for example, in “Goetz, SM; Peterchev, AV; Weyh, T., "Modular Multilevel Converter With Series and Parallel Module Connectivity: Topology and Control," Power Electronics, IEEE Transactions on, vol.30, no.1, pp.203, 215, 2015. doi: 10.1 109/TPEL .2014.2310225. By configuring an electrical interconnection of energy stores in modules and by switching modulation between switching states to form any intermediate states, voltage differences are generated between two connection terminals, for example to a charging station and to a traction battery of an electric car.

Further advantages and refinements of the invention result from the description and the attached drawing.

It goes without saying that the features mentioned above and those still to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

• 1 zeigt schematisch eine von einem Halbleitermodul umfasste Ausgestaltung der erfindungsgemäßen Schaltung.
• 2 zeigt schematisch eine von einem Halbleitermodul umfasste weitere Ausgestaltung der erfindungsgemäßen Schaltung.
• 3 zeigt schematisch ein Ersatzschaltbild zu der in 2 gezeigten weiteren Ausgestaltung der erfindungsgemäßen Schaltung.
• 4 zeigt schematisch einen Schwingkreis in einem weiteren Ersatzschaltbild der erfindungsgemäßen Schaltung.
• 5 zeigt graphisch zeitliche Verläufe von in einer Ausführungsform des erfindungsgemäßen Verfahrens auftretenden Strömen und Spannungen.
• 6 zeigt graphisch zeitliche Verläufe von in einer weiteren Ausführungsform des erfindungsgemäßen Verfahrens auftretenden Strömen und Spannungen.

The figures are described in a coherent and comprehensive manner, and the same reference symbols are assigned to the same components.

• 1 shows schematically an embodiment of the circuit according to the invention, which is comprised by a semiconductor module.
• 2 shows schematically a further embodiment of the circuit according to the invention, which is comprised by a semiconductor module.
• 3 shows schematically an equivalent circuit diagram for the in 2 shown further embodiment of the circuit according to the invention.
• 4 shows schematically an oscillating circuit in a further equivalent circuit diagram of the circuit according to the invention.
• 5 shows graphically time curves of currents and voltages occurring in an embodiment of the method according to the invention.
• 6 shows graphically time curves of currents and voltages occurring in a further embodiment of the method according to the invention.

In 1 an embodiment of the circuit 100 according to the invention, which is comprised by a semiconductor module, is shown schematically. The circuit 100 with a high-side semiconductor switch 110 and a low-side capacitance 250 has an upper input 101 and a lower input 102, which is connected to a high-voltage (HV) direct current. The high-side semiconductor switch 110 is, for example, an N-channel MOSFET or alternatively an N-channel IGBT. The high-side semiconductor switch 110 has a drain connection 111, a source connection 112 and a gate connection 113. A coil 130 is arranged after an upper output of the half-bridge located between the high-side semiconductor switch 110 and the low-side capacitance 250 . This forms an upper output 103 of the semiconductor module. The lower output of the semiconductor module 104 is formed by a lower output of the circuit 100 . A low-pass capacitor 140 is optionally present, which forms a low-pass filter together with the coil 130 . The semiconductor module has a capacitance belonging to it, which is created by electronic components such as the high-side semiconductor switch 110 and the low-side capacitance 250 and other additional components located in the semiconductor module, such as other half-bridges with, for example, temporarily open switches is intrinsic.

In 2 a further embodiment 200 of the circuit according to the invention, which is comprised by a semiconductor module, is shown schematically. A low-side semiconductor switch 120 has a drain connection 121 , a source connection 122 and a gate connection 123 . According to the invention, the low-side semiconductor switch 120 is in the open position. The low-side semiconductor switch 120 is also an N-channel MOSFET, for example, or alternatively an N-channel IGBT. In the open state, the low-side semiconductor switch 120 has a low-side capacitance, which represents a junction capacitance, and thus contributes to the semiconductor module capacitance.

In 3 is a schematic equivalent circuit diagram 300 for the in 2 shown embodiment of the circuit according to the invention. For this purpose, in both semiconductor switches 110 or reference numbers 120 in 2 a respective freewheeling diode 214, 224, which is intrinsically present, is drawn in. Since the in 2 Drawn low-side semiconductor switch 120 is permanently driven in the open position, this can be omitted in the equivalent circuit 300 and is free by its running diode 224 replaced. In addition, the low-side capacitance 250 of the semiconductor module, which usually develops parasitically and is normally undesirable in other circuit applications, is shown between the upper output of the half-bridge and the lower output of the half-bridge.

$$\begin{array}{cc}{i}_{C,OSS}+i_L=0& i_L=-C_{OSS}\frac{d{u}_{C,OSS}}{dt}\end{array}$$

In 4 an oscillating circuit 400 is shown schematically in a further equivalent circuit diagram of the configuration of the circuit according to the invention. The resonant circuit 400 can be used as an equivalent circuit for the in 1 circuit 100 shown can be assumed if no current flows through the high-side semiconductor switch 110. During operation, the resonant circuit 300 formed by the coil 130 with inductance L and low-side capacitance 250 with capacitance value Coss has a coil current i _L 331, a capacitor voltage u _C,OSS 351 and a battery voltage u _Cb 305 between the semiconductor module outputs 103, 104 . At a point in time t=0 the coil current i _L 331 is denoted by an initial current i _L (t=0)= i _L,0 and the capacitor voltage uc,oss 351 by u _C,OSS (t=0)=u _DC , where u _DC is an intermediate circuit voltage. The network equations are then: $$y_{C,OSS}-{\mathrm{and}}_L={\mathrm{and}}_{Cb}$$

$$\begin{array}{cc}{i}_{C,OSS}+i_L=0& i_L=-C_{OSS}\frac{\mathrm{i.e}{\mathrm{and}}_{C,OSS}}{\mathrm{i.e}t}\end{array}$$

The component equations are: $$\begin{array}{cc}{i}_L=C_{OSS}\frac{\mathrm{i.e}{\mathrm{and}}_{C,OSS}}{\mathrm{i.e}t}& {\mathrm{and}}_L=L\frac{\mathrm{i.e}{i}_L}{\mathrm{i.e}t}\end{array}$$

If the derivative of u _Cb over time, i.e. its change over time, in Eq. 1 equal to zero, the resulting differential equations for the coil current are as follows $$\begin{array}{cc}\frac{i_{C,OSS}}{C_{OSS}}-L\frac{{\mathrm{i.e}}^2{i}_L}{\mathrm{i.e}{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="DE102020124596A1\_0010.png,DE102020124596A1\_0011.png"\; state="\{\{state\}\}">t</figure-callout>}}^2}=0& -\frac{i_L}{C_{OSS}}-L\frac{{\mathrm{i.e}}^2{i}_L}{\mathrm{i.e}{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="DE102020124596A1\_0010.png,DE102020124596A1\_0011.png"\; state="\{\{state\}\}">t</figure-callout>}}^2}=0\end{array}$$

By solving the differential equations in Eq. 4, an output voltage 305 of the semiconductor module and the coil current 331 can be calculated analytically. Initial conditions are known from the given intermediate circuit voltage and battery voltage. Furthermore, the initial current i _L,0 can also be calculated. This results from a current ripple, which in turn can be calculated from the voltages that occur.

In 5 shows graphically time curves of currents and voltages occurring in an embodiment of the method according to the invention. In a graph 410, a time axis 401 in 10 ⁻⁵ s is shown as the x-axis, while a current value 412 in amperes is plotted as the y-axis. In a graph 420, a time axis 401 in 10 ^-5 s is again selected as the x-axis, while a voltage 422 in volts is plotted as the y-axis. An intermediate circuit voltage 424 present for the graph shown is u _DC =780 V. The high-side semiconductor switch is controlled by a control voltage 418 present at its gate. The resulting (measured) coil current 417 has a minimum current value of approximately −4.8 A and a maximum current value of approximately 4.8 A. It is set in a time range 413 by the closed high-side semiconductor switch from the intermediate circuit, determined in a time range 414 by the high-side freewheeling diode, and driven in a time range 416 by the discharging low-side capacitance. If the high-side semiconductor switch is open in addition to the low-side semiconductor switch, an oscillating circuit can form due to the low-side capacitance and coil, the current curve of which approaches an ideal (theoretical) current curve 419 . The course of the coil current 417 shown shows that the coil current runs within small current amounts below 5 A with the aid of the method according to the invention and can be adjusted despite the HV intermediate circuit voltage by simple control, e.g. using a PI controller. The graph 420 describes a measured profile of the capacitor voltage 426 and a simulated profile 425 at the low-side capacitance. While the intermediate circuit voltage 424 prevails in the closed state of the high-side semiconductor switch, a minimum voltage 423 of 85 V is reached for the open state. In this case, the voltage curve can be approximately described by a voltage curve 429 for an ideal LC resonant circuit.

In 6 shows graphically time curves of currents and voltages occurring in a further embodiment of the method according to the invention. In a graph 500, a time axis 501 in 10 ^-5 s is shown as the x-axis and a positive current or voltage axis is shown as the y-axis. The method according to the invention controls the gate of the high-side semiconductor switch by means of the gate control voltage 518, so that a coil current 517 between a current value minimum 503 and a current value maximum 505 is set. A current 510 filtered by a low-pass filter has a time-averaged current value 504 .

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102017123348 A1 [0003]
• US 2012/0223575 A1 [0006]
• DE 102019102998 A1 [0007]
• US 2018/0361861 A1 [0008]

Claims (14)

A method for setting small currents for rapid battery charging, in which a semiconductor module has a circuit (100) with a high-side semiconductor switch (110) and a low-side capacitance (250), in which at an input (101, 102) a high-voltage DC voltage is applied to the circuit, in which case a coil (130) is arranged after an upper output of the circuit (100) located between the high-side semiconductor switch (110) and the low-side capacitance (250). and thus an upper output (103) of the semiconductor module is formed, in which a lower output (104) of the semiconductor module is formed by a lower output of the circuit (100), in which the upper output (103) and the lower output (104) of the semiconductor module are connected to two poles of a battery, with the coil (130) together with the low-side capacitance (250) forming an oscillating circuit (400) with an oscillating circuit frequency, by means of controlling the high-side semiconductor circuit alter (110) is operated against the oscillating circuit (400) by the high-side semiconductor switch (110) being switched on in a manner adapted to the oscillating circuit frequency during a falling coil current (331), the coil current (331) then rising and thereby a current value minimum (503) is defined, and the high-side semiconductor switch is switched off during a rising coil current (331), the coil current (331) then falls and a current value maximum (505) is thereby defined, and by selecting a respective switch-on and switch-off time of the high side semiconductor switch (110), an output current (510) of the semiconductor module is regulated with current values between the current value minimum (503) and the current value maximum (505). procedure after claim 1 , the high-side semiconductor switch (110) being switched on when the oscillating circuit (300) has the smallest negative current value and being switched off when the oscillating circuit (300) has the greatest positive current value, resulting in a mean current value over time of 0 A. Method according to one of the preceding claims, in which the low-side capacitance (250) is formed by a capacitor. Procedure according to one of Claims 1 or 2 , in which the low-side capacitance (250) is formed by a low-side semiconductor switch (120). Method according to one of the preceding claims, in which the low-side capacitance (250) is selected to be sufficiently large so that it completely provides a charge for a coil current (331) during a reversal process and thus gap-free operation can be and/or is carried out . Method according to one of the preceding claims, in which a highly non-linear behavior, in which a capacitance value increases sharply at low voltage, is selected for the low-side capacitance (250). Method according to one of the preceding claims, in which a low-pass filter is formed by arranging a low-pass capacitor (140) between the terminals of the output (103, 104) of the semiconductor module together with the coil (130), whereby the output current (510) has a constant time profile having. Circuit (100, 200, 300) for setting small currents during rapid battery charging, in which a semiconductor module has a high-side semiconductor switch (110) and a low-side capacitance (250), in which an input (101 , 102) of the circuit (100, 200, 300) a high-voltage DC voltage is applied, at which, after an upper output of the circuit (100 , 200, 300) a coil (130) is arranged and thus an upper output (103) of the semiconductor module is formed, in which a lower output (104) of the semiconductor module is formed by a lower output of the circuit (100, 200, 300). , in which the lower output (103) and the upper output (104) of the semiconductor module are connected to two poles of a battery, the coil (130) with the low-side capacitance (250) being configured to form an oscillating circuit (400 ) with an oscillating circuit frequency, and a control for this purpose k is configured to operate the high-side semiconductor switch (110) against the oscillating circuit (400) by switching on the high-side semiconductor switch (110) during a falling coil current (331) and the coil current (331) thereupon, adapted to the oscillating circuit frequency increases, thereby defining a current value minimum (503), and it turns off the high-side semiconductor switch (110) during a rising coil current (331) and the coil current (331) then falls, whereby a current value maximum (505) is defined, and wherein an output current (510) of the semiconductor module with current values between the current value minimum (503) and the current value maximum (505) can be and/or is regulated by selecting a respective switch-on and switch-off time of the high-side semiconductor switch (110). Circuit (100) after claim 8 , in which the low-side capacitance (250) is formed by a capacitor. Circuit (100, 200, 300) after claim 8 , In which the low-side capacitance (250) is formed by a low-side semiconductor switch (120). Circuit (100, 200, 300) after one of Claims 8 until 10 , in which the low-side capacitance (250) is chosen to be sufficiently large so that it completely provides a charge for a coil current (331) during a reversal process and thus a gap-free operation can be carried out and/or takes place. Circuit (100, 200, 300) after one of Claims 8 until 11 , in which the low-side capacitance (250) exhibits a strongly non-linear behavior in which a capacitance value increases sharply at low voltage. Circuit (100, 200, 300) after one of Claims 8 until 12 , in which a low-pass filter is formed by arranging a low-pass capacitor (140) between the terminals of the output (103, 104) of the semiconductor module together with the coil (130). Use of the circuit (100, 200, 300) for setting small currents in a battery rapid charge, the semiconductor module being an inverter with a plurality of half-bridges and with a circuit (100, 200, 300) according to claims 8 until 13 is designed and wherein a method according to one of Claims 1 until 7 is performed.

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