Electronic circuit for electrical power consumption from a supply voltage circuit

Abstract

The invention relates to an electronic circuit (ES) for electrical power consumption from a supply voltage circuit (IN), wherein the supply voltage circuit (IN) has a supply voltage (U_IN); characterised in that the electronic circuit (ES) comprises a voltage conversion circuit (SWS), which is designed to convert the supply voltage (U_IN) into an internal voltage (U_INT); in that the electronic circuit (ES) comprises an electrical resistor assembly (R) which is designed for electrical power consumption and comprises at least one electrical resistor (R1...R18); and in that the electronic circuit (ES) comprises a first electronic switch (FET1) which is designed to open and close a circuit which is fed via the internal voltage (U_INT), and which passes through the electrical resistor assembly (R).

Description

[0001] Electronic circuit for electrical power consumption from a supply voltage circuit

[0002] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identity are included.

[0003] DESCRIPTION INTRODUCTION

[0004] The invention relates to an electronic circuit for receiving electrical power from a supply voltage circuit, wherein the supply voltage circuit has a supply voltage according to the preamble of patent claim 1. Furthermore, the invention relates to a method for operating an electronic circuit.

[0005] STATE OF THE ART

[0006] Such electronic circuits, also known as brake chopper modules, are used, for example, in the intermediate voltage circuit of power converters. They absorb electrical regenerative power or energy, typically generated by drives during braking, and convert it into thermal energy to limit the increase in the intermediate voltage or supply voltage.

[0007] A well-known, particularly powerful application is that of the tram, which feeds the regenerative energy back into load resistors mounted on the roof of the tram.

[0008] In industrial applications, regenerative power is in the range of 10 to 1000 W, and the duration of the regenerative phase is in the range of 100 ms to a few seconds. Here, too, the regenerative energy must be converted into thermal energy, since it must be temporarily stored in a capacitor or secondary cells and then drawn from the buffer in some form. Similar to trams, this is done with powerful, thermally resilient load resistors.

[0009] The technical problem is that different currents occur depending on the braking power. If the circuit is designed for 24V systems, for example, with an activation threshold of 26...28V, it must draw around 40A from the DC network for a high braking power of 1000W. The resistors are then dimensioned with 0.6250hm. If this electronic switch or brake chopper module is used in 48V systems and 1000W is also to be drawn, an average current of 20A is required for an activation threshold of 50...52V. If the resistors remain unchanged, this means clocked activation of the resistors, here for example with a switching sequence of 0A / 80A, since the resistors remain unchanged at 0.6250hm and this results in this high current at 50V.

[0010] Depending on the input and output capacitances involved, the switching sequence mentioned runs at a clock frequency of a few 100Hz down to the lower kHz range and leads to massive interference on the supply lines to the electronic circuit or to the brake chopper module, in particular due to the inductance of the supply lines.

[0011] A further problem is that with lower and increasing power or braking power requirements, even in the lower voltage range, continuous switching of the electrical resistors is not possible; instead, a pulsed switching sequence is required. A braking power of 800W / 26V results in a switching sequence with pulses of 0A / 40A with a duty cycle of 80%.

[0012] Medium-frequency current pulses of this magnitude can lead to significant voltage fluctuations on the DC supply, can cause unstable behavior, and thus represent a source of EMC interference. Another technical problem is that connecting multiple electronic circuits or brake chopper modules in parallel can lead to uncontrolled switching sequences, as the electronic circuits or brake chopper modules must react to the fluctuating DC voltage due to the asynchronously switching parallel devices.

[0013] The invention is based on the object of specifying an electronic circuit for electrical power consumption from a voltage intermediate circuit, which is suitable for a wide range of different supply voltages with simultaneously high power consumption and at the same time causes minimal interference or feedback in the supply voltage circuit and on supply lines from the supply voltage circuit to the electronic circuit.

[0014] SOLUTION TO THE TASK

[0015] This object is achieved by an electronic circuit of the type mentioned above having the features according to the independent patent claim. This object is also achieved by a method for operating an electronic circuit according to the invention. Advantageous embodiments of the present invention are described in the dependent claims.

[0016] According to the invention, the object is achieved by an electronic circuit of the type mentioned at the outset, in which the electronic circuit comprises a voltage conversion circuit which is designed to convert the supply voltage into an internal voltage; the electronic circuit comprises an electrical resistance arrangement which is designed to absorb electrical power and comprises at least one electrical resistance; and the electronic circuit comprises a first electronic switch which is designed to close and open an electrical circuit which is fed via the internal voltage and runs via the electrical resistance arrangement.

[0017] This measure decouples the electrical resistance arrangement and the first electronic switch from the supply voltage circuit, resulting in no or only minimal repercussions from the electronic circuit on the supply voltage circuit. Furthermore, the electronic circuit is suitable for a wide range of different supply voltages with simultaneously high electrical power consumption, since the electrical resistance arrangement can be designed for the internal voltage. The electrical resistance arrangement ultimately serves to absorb the electrical power and release it as thermal power to the environment.

[0018] A high clock frequency of the voltage conversion circuit, combined with small capacitors at the input of the electronic circuit, allows for a very effective filtering effect, so that a direct current is effectively drawn. The duty cycle allows the electrical power drawn to be precisely regulated over a very wide range, thus enabling wide-range operation. The inductance of the cables also no longer affects the braking behavior due to the drawn direct current.

[0019] According to the claim, the electronic circuit comprises a first electronic switch designed to close and open a circuit fed by the internal voltage, which runs via the electrical resistance arrangement. In other words, this means that the electronic circuit comprises a first electronic switch designed to connect the electrical resistance arrangement to the internal voltage and to disconnect it from the internal voltage. The first electronic switch can be arranged upstream of or downstream of the resistance arrangement.

[0020] It is advantageous if the voltage conversion circuit is designed as a DC-DC converter, in particular as a boost converter, buck converter, boost-buck converter, Cuk converter, SEPIC converter or Zeta converter.

[0021] These voltage conversion circuits have proven particularly suitable for converting the supply voltage into the internal voltage. Furthermore, these voltage conversion circuits result in minimal interference with the supply voltage circuit, as they decouple the switching operations of the electronic switch from the supply voltage circuit.

[0022] Furthermore, it is advantageous if the electrical resistance arrangement comprises a plurality of electrical resistors connected in series and / or parallel.

[0023] This measure results in an improved distribution of the electrical power to the electrical resistors and thus an improved release of the resulting thermal energy.

[0024] It is advantageous if the voltage conversion circuit comprises a second electronic switch.

[0025] It is particularly advantageous if the internal voltage is different from the supply voltage, in particular higher than the supply voltage.

[0026] This measure allows the resistor arrangement to be designed for and optimized for an internal voltage. The design of the resistor arrangement is therefore essentially independent of the applied supply voltage. It is particularly advantageous if the internal voltage is greater than the supply voltage, in particular greater than the highest expected supply voltage. It is also advantageous if the internal voltage is lower than the supply voltage, in particular lower than the lowest expected supply voltage.

[0027] It is advantageous if the electronic circuit comprises a first control circuit which is designed to control the first electronic switch as a function of the internal voltage.

[0028] This measure allows the power absorbed by the electrical resistance arrangement to be controlled as a function of the internal voltage. At a high internal voltage, the first electronic switch can be controlled such that the electrical resistance arrangement absorbs a large amount of electrical power. At a low internal voltage, the first electronic switch can be controlled such that the electrical resistance arrangement absorbs a small amount (or no power at all).

[0029] It is advantageous if the electronic circuit comprises a second control circuit which is designed to control the voltage conversion circuit, in particular the second electronic switch, as a function of the supply voltage.

[0030] By this measure, the supply voltage, in particular its value, can be used to regulate the electrical power consumption of the electronic circuit from the supply voltage circuit. At a higher supply voltage, the voltage conversion circuit can be controlled in such a way that it consumes a greater electrical power or transfers it to the electrical resistance arrangement. At a lower supply voltage, the voltage conversion circuit can be controlled in such a way that it consumes a lesser (or no) electrical power or transfers it to the electrical resistance arrangement. The voltage conversion circuit is therefore not used in the known way, in which a controller regulates a variable input voltage to a constant output voltage and the regulated variable is the output voltage.Likewise, the difference from known controls for voltage conversion circuits is that the absorbed or transmitted electrical power is increased with increasing target voltage (= supply voltage), rather than with decreasing target voltage. The object of the invention is further achieved by a method for operating an electronic circuit according to one of claims 1 to 7, wherein the voltage conversion circuit converts the supply voltage into the internal voltage.

[0031] Thanks to this measure, the electrical power absorbed by the electronic circuit is not dependent on the supply voltage. The design of the electrical resistance arrangement (with regard to ohm value, heat capacity, and heat dissipation) defines the electrical power absorbed by the electronic circuit, independent of the supply voltage. A absorbed electrical power of, for example, 1000W can be provided equally across a range of, for example, 20V...60V with an unchanged electrical resistance arrangement.

[0032] It is advantageous if the internal voltage is higher than the highest expected supply voltage or lower than the lowest expected supply voltage at the respective operating point.

[0033] It is particularly advantageous if the internal voltage is higher than the supply voltage.

[0034] These measures allow the electrical circuit to be used for a wider range of different supply voltages. It is advantageous if the first electronic switch is controlled depending on the internal voltage.

[0035] This measure allows the power absorbed by the electrical resistance arrangement to be controlled as a function of the internal voltage. At a high internal voltage, the first electronic switch can be controlled such that the electrical resistance arrangement absorbs a large amount of electrical power. At a low internal voltage, the first electronic switch can be controlled such that the electrical resistance arrangement absorbs a small amount (or no power at all).

[0036] Furthermore, it is advantageous if a target range is specified for the internal voltage; the first electronic switch is switched to a permanently conductive state when the internal voltage is above the target range; the first electronic switch is switched to a permanently blocking state when the internal voltage is below the target range; and the first electronic switch is controlled with a first switching sequence which has a first clock frequency, by means of which the first electronic switch is alternately switched to a conductive and a blocking state when the internal voltage is in the target range.

[0037] This measure allows the electrical power absorbed by the electrical resistance arrangement to be adjusted even better.

[0038] Furthermore, it is advantageous if the electrical power transmitted via the voltage conversion circuit is regulated as a function of the supply voltage.

[0039] This measure allows for a better response to the voltage conditions prevailing in the supply voltage circuit. A higher supply voltage, for example, means that electrical power is fed back into the supply voltage circuit. In this case, the electrical energy transferred by the voltage conversion circuit must be increased. This electrical energy can then be absorbed by the electrical resistance arrangement.

[0040] It is particularly advantageous if a setpoint or a setpoint range is specified for the supply voltage and that this setpoint or setpoint range is increased as the transmitted power of the voltage conversion circuit increases.

[0041] This measure enables parallel operation of several electronic circuits or brake chopper modules. If the control of the voltage conversion circuit is influenced in such a way that the setpoint or setpoint range for the control voltage (= supply voltage) is increased as the electrical power consumption or current consumption increases, then a so-called "soft characteristic curve" is obtained. A first electronic circuit thus regulates its setpoint or setpoint range upwards, while a second electronic circuit connected in parallel with an initially low current consumption still has a lower setpoint or setpoint range and therefore takes on more current. In this way, the modules connected in parallel share the electrical power or current consumption equally.

[0042] It is particularly advantageous if the first electronic switch is controlled with a first switching sequence which has a first clock frequency; the voltage conversion circuit is controlled with a second switching sequence which has a second clock frequency; and the second clock frequency is higher than the first clock frequency. As a result of this measure, only the second, higher clock frequency of the voltage conversion circuit is effective externally, i.e. to the supply voltage circuit. A high clock frequency means that filter circuits can be built with small components which filter the clocking of the voltage conversion circuit in such a way that only a small current ripple occurs externally.

[0043] It is advantageous if the voltage conversion circuit is deactivated via a deactivation signal when the internal voltage exceeds a specified value.

[0044] This measure increases the safety and fault tolerance of the electronic circuit.

[0045] FIGURE DESCRIPTION

[0046] In the following, the invention is described and explained in more detail with reference to the exemplary embodiments shown in the figures.

[0047] Examples include:

[0048] Figure 1 shows an exemplary embodiment of an electronic circuit according to the invention,

[0049] Figure 2 shows an exemplary embodiment of a control for a microcontroller for an electronic circuit according to the invention.

[0050] Fig. 1 shows an exemplary embodiment of an electronic circuit according to the invention.

[0051] The electrical circuit ES can be connected to a supply voltage circuit IN using the two connection points shown on the left. The supply voltage circuit IN has, for example, a supply voltage U_IN of 24V to 48V. In this exemplary embodiment, this supply voltage U_IN is a direct voltage. The electronic circuit comprises an electrical resistor arrangement R. In this exemplary embodiment, the electrical resistor arrangement is formed from 18 electrical resistors R1... R18. These electrical resistors R1... R18 are, as shown in Fig. 1, connected in a combination of series and parallel circuits. Furthermore, the electronic circuit ES comprises a first electronic switch FETI which is designed to close and open a circuit which is fed via the internal voltage U_INT and runs via the electrical resistor arrangement R.In this exemplary embodiment, the first electronic switch FETI is arranged downstream of the electrical resistance arrangement R in series with it. The first electronic switch FETI can, for example, also be arranged upstream of the electrical resistance arrangement R in series with it. The first electronic switch FETI is controlled via a first control circuit. The first control circuit is designed to control the first electronic switch FETI as a function of the internal voltage U_INT. The first electronic switch FETI can be controlled such that it is continuously conductive, continuously blocked or, if it is controlled with a switching sequence, alternately conductive or blocked. The control influences the electrical power consumed by the electrical resistance arrangement R. The first switching sequence has a first clock frequency.

[0052] In this embodiment, the first electronic switch FETI is designed as a field-effect transistor. Alternatively, a bipolar transistor could be used.

[0053] An electronic safety switch SAFETYFET can be arranged in series with the first electronic switch FETI. This is opened in the event of a fault, for example, if the first electronic switch FETI fails or malfunctions, to open the circuit fed by the internal voltage U_INT and running through the electrical resistor arrangement R. In this embodiment, the electronic safety switch SAFETYFET is designed as a field-effect transistor. Alternatively, a bipolar transistor could be used.

[0054] A voltage conversion circuit SWS is arranged at the input of the electronic circuit ES. In this exemplary embodiment, the voltage conversion circuit SWS is a step-up converter or a boost converter. Other types of voltage conversion circuits SWS, such as step-down converters, step-up / step-down converters, Cuk converters, SEPIC converters or zeta converters, can also be used. In this exemplary embodiment, the voltage conversion circuit SWS comprises, among other things, a second electronic switch FET2, a first capacitor CI, a second capacitor C2, a third capacitor C3, a first inductance LI and a second inductance L2. In this exemplary embodiment, the second electronic switch FET2 is designed as a field-effect transistor. Alternatively, a bipolar transistor could be used, for example.

[0055] The voltage conversion circuit SWS converts the supply voltage U_IN into an internal voltage U_INT, which is supplied to the electrical resistance arrangement. The internal voltage U_INT generated by the voltage conversion circuit SWS is preferably higher than the supply voltage U_IN. The supply voltage U_IN and the internal voltage U_INT are preferably DC voltages.

[0056] The electronic circuit ES further comprises a second control circuit that controls the voltage conversion circuit SWS. In the present embodiment, the second control circuit comprises a PWM controller that controls a second electronic switch FET2 of the voltage conversion circuit SWS. The second control circuit generates a second switching sequence that has a second clock frequency. Due to this two-stage mode of operation, the resistors are decoupled from the supply voltage applied to the input.

[0057] In one embodiment, the voltage conversion circuit SWS reacts with the help of the second control circuit to an excessively high supply voltage U_IN. The voltage conversion circuit becomes active and withdraws electrical energy from the supply voltage circuit. The higher the supply voltage U_IN is above the activation threshold, the more electrical energy is withdrawn from it. In this embodiment, this electrical energy is transformed by the boost converter into a higher internal voltage U_INT, so that the output-side capacitor CI of the voltage conversion circuit SWS or of the boost converter is charged and the internal voltage U_INT increases.

[0058] This internal voltage U_INT is regulated by the first control circuit in such a way that when the upper switching threshold (U_INT > U_INT_SOLL_HI) is reached, the electrical resistance arrangement R is activated so that the capacitors CI are discharged again. The design of the electrical resistance arrangement R must be selected in such a way that when activated it can draw more electrical energy from the capacitor CI than the voltage conversion circuit SWS or the boost converter can add. The internal voltage U_INT at the capacitor CI therefore drops until the electrical resistance arrangement R is deactivated again when the lower switching threshold (U_INT < U_INT_SOLL_LO) is undershot. The internal voltage U_INT at the capacitor CI then rises again.

[0059] If the supply voltage circuit can only supply a small amount of excess electrical energy, the voltage conversion circuit SWS or the boost converter is operated with less electrical power in order to maintain voltage equilibrium (the second control circuit regulates to a constant supply voltage) at the input. With less electrical power at the voltage conversion circuit SWS or the boost converter, the capacitor CI is charged more slowly. The electrical resistance arrangement R does not have to be switched on as frequently, i.e. it cycles less frequently. Its active time is also shorter because with lower electrical power supply and unchanged electrical power consumption (by the electrical resistance arrangement R) the capacitor CI reaches the lower switching threshold more quickly.

[0060] A significant advantage of the invention is that, thanks to the claimed circuit, a second clock frequency for the voltage conversion circuit SWS, which is for example in a range from 20 kHz to 300 kHz, can be higher than a first clock frequency for the first electronic switch FETI, which is for example in a range from 100 Hz to 2 kHz. As a result, only the second, higher clock frequency of the voltage conversion circuit is effective towards the outside, i.e. towards the supply voltage circuit. A high clock frequency means that filter circuits can be constructed using small components which filter the clocking of the voltage conversion circuit in such a way that only a small current ripple occurs towards the outside.

[0061] In addition, there is also load sharing management so that several electronic circuits can be operated in parallel on a common supply voltage circuit. This is done via a sloped control characteristic curve, where the regulated voltage (e.g. 26V for a 24V nominal voltage or 50V for 48V nominal voltage) increases with increasing electrical power as the electrical power consumed. A typical value here at 24V is the onset of the braking effect at 26V; at maximum power consumption this would then rise to 27V, for example. A parallel electrical circuit with a braking onset voltage of 26.2V, for example (due, for example, to component values ​​differing due to tolerances) would therefore also become active and provide support as the power consumption increases through the first electrical circuit.The electrical circuits therefore start with a low power consumption and increase it as the voltage on the supply voltage circuit rises. This gives the other parallel electrical circuits a chance to also take over some of the power to reduce the supply voltage. The part of the electronic circuit shown on the right in Fig. 1, starting with diode D3, is a subcircuit for providing a 12V and a 3.3V supply voltage to power other components of the electronic circuit, such as a microcontroller.

[0062] Reference symbol list

[0063] ES Electronic Circuit

[0064] IN supply voltage circuit U_IN supply voltage

[0065] U_IN_SOLL Setpoint / setpoint range of the supply voltage

[0066] U_INT Internal voltage

[0067] U_INT_SOLL Target range of the internal voltage R Electrical resistance arrangement R1 . . . R18 Electrical resistance

[0068] FETI First electronic switch

[0069] FET2 Second electronic switch

[0070] SAFETYFET Electronic safety switch

[0071] SWS voltage conversion circuit

Claims

Patent claims 1. Electronic circuit (ES) for receiving electrical power from a supply voltage circuit (IN), wherein the supply voltage circuit (IN) has a supply voltage (U_IN); characterized in that the electronic circuit (ES) comprises a voltage conversion circuit (SWS) which is designed to convert the supply voltage (U_IN) into an internal voltage (U_INT); in that the electronic circuit (ES) comprises an electrical resistance arrangement (R) which is designed to receive electrical power and comprises at least one electrical resistor (R1...R18); and in that the electronic circuit (ES) comprises a first electronic switch (FETI) which is designed to close and open a circuit which is fed via the internal voltage (U_INT) and which runs via the electrical resistance arrangement (R).

2. Electronic circuit (ES) according to claim 1, characterized in that the voltage conversion circuit (SWS) is designed as a DC-DC converter, in particular as a boost converter, buck converter, boost-buck converter, Cuk converter, SEPIC converter or zeta converter.

3. Electronic circuit (ES) according to one of the preceding claims, characterized in that the electrical resistor arrangement (R) comprises a plurality of electrical resistors (R1...R18) connected in series and / or in parallel.

4. Electronic circuit (ES) according to one of the preceding claims, characterized in that the voltage conversion circuit (SWS) comprises a second electronic switch (FET2).

5. Electronic circuit (ES) according to one of the preceding claims, characterized in that the internal voltage (U_INT) is different from the supply voltage (U_IN), in particular greater than the supply voltage (U_IN).

6. Electronic circuit (ES) according to one of the preceding claims, characterized in that the electronic circuit (ES) comprises a first control circuit which is designed to control the first electronic switch (FETI) as a function of the internal voltage (U_INT).

7. Electronic circuit (ES) according to one of the preceding claims, characterized in that the electronic circuit (ES) comprises a second control circuit which is designed to control the voltage conversion circuit (SWS), in particular the second electronic switch (FET2), as a function of the supply voltage (U_IN).

8. Method for operating an electronic circuit (ES) according to one of claims 1 to 7, characterized in that the voltage conversion circuit (SWS) converts the supply voltage (U_IN) into the internal voltage (U_INT).

9. The method according to claim 8, characterized in that the internal voltage (U_INT) is higher than the highest expected supply voltage (U_IN) or lower than the lowest expected supply voltage (U_IN) at the respective operating point.

10. Method according to one of claims 8 or 9, characterized in that the internal voltage (U_INT) is greater than the supply voltage (U_IN).

11. Method according to one of claims 8 to 10, characterized in that the first electronic switch (FETI) is controlled as a function of the internal voltage (U_INT).

12. Method according to one of claims 8 to 11, characterized in that a target range (U_INT_SOLL) is specified for the internal voltage (U_INT), that the first electronic switch (FETI) is switched to a permanently conductive state when the internal voltage (U_INT) is above the target range (U_INT_SOLL), that the first electronic switch (FETI) is switched to a permanently blocking state when the internal voltage (U_INT) is below the target range (U_INT_SOLL) and that the first electronic switch (FETI) is controlled with a first switching sequence which has a first clock frequency, by means of which the first electronic switch (FETI) is alternately switched to a conductive and a blocking state when the internal voltage (U_INT) is in the target range (U_INT_SOLL).

13. Method according to one of claims 8 to 12, characterized in that an electrical power transmitted via the voltage conversion circuit (SWS) is regulated as a function of the supply voltage (U_IN).

14. Method according to one of claims 8 to 13, characterized in that a setpoint value or a setpoint range (U_IN_SOLL) is specified for the supply voltage (U_IN) and that this setpoint value or setpoint range (U_IN_SOLL) is increased with increasing transmitted power of the voltage conversion circuit (SWS).

15. Method according to one of claims 8 to 14, characterized in that the first electronic switch (FETI) is controlled with a first switching sequence which has a first clock frequency, that the voltage conversion circuit (SWS) is controlled with a second switching sequence which has a second clock frequency, and that the second clock frequency is greater than the first clock frequency.

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