DE102020118024A1 - Technology for activating a control of a power stage - Google Patents

Abstract

One aspect relates to a device (100) for enabling control of a power stage (200) of an electrical machine (300). The device comprises a first input (102) for detecting a safety function signal and a second input (104) for detecting a reference potential of the safety function signal. The device also includes one or at least two switch-off paths (106) of the control. Each switch-off path (106) includes an input coupler (110), which is connected on the input side between the first input (102) and the second input (104) and is designed to transmit the safety function signal in a manner that is electrically isolated from the inputs (102, 104). ; at least one output (130) for driving a switch of a half-bridge of the power stage (200); and at least one modulation logic unit (120) which is designed to logically link a modulation signal (166; 168) assigned to the respective switch and the safety function signal transmitted by the respective input coupler (110) and to output it at the output (130) as a modulation signal (108) which can be activated .

Description

The invention relates to a technique for enabling control of a power stage of an electrical machine. In particular, without being limited thereto, a device for enabling a power stage and a frequency converter equipped therewith are disclosed.

To drive an electric motor, there are already frequency converters with a function for safe torque interruption, which is technically referred to as the "Safe Torque Off" function (STO function). The document
DE 10 2011 003 922 A1 describes such a frequency converter whose STO input signal is dynamized, ie is time-dependent. A supply voltage generating unit eliminates a DC component. A supply voltage for transmission means and drivers for controlling a power stage is generated only when a time-dependent signal is present. If the dynamization fails, the supply voltage is automatically interrupted in accordance with the principle of reliability (technically also: fail-safe).

However, the dynamic signal must be generated for this principle. This can be done, for example, by a microcontroller or by a different type of clock generator. In addition, the dynamic signal must be evaluated by a processing unit.

While such a design can be implemented with reasonable additional effort for frequency converters that require a microcontroller for other functions, the use of a microcontroller or other complex circuits solely for dynamization is disproportionate, for example with simple variable speed starters. In particular, no STO function is known for simple variable speed starters.

The invention is therefore based on the object of specifying a technique for safely enabling the control of a power stage, in particular an STO function, which does not require complex dynamization of the input signal, and which can preferably also be integrated into a simple variable-speed starter.

The object is solved with the features of the independent claims. Expedient refinements and advantageous developments of the invention are specified in the dependent claims.

Exemplary embodiments of the invention are described below with partial reference to the figures.

• - einen Eingangskoppler, der eingangsseitig zwischen den ersten Eingang und den zweiten Eingang geschaltet ist und dazu ausgebildet ist, das Sicherheitsfunktionssignal galvanisch getrennt von den Eingängen zu übertragen;
• - mindestens einen Ausgang zur Ansteuerung eines Schalters einer Halbbrücke der Leistungsstufe; und
• - mindestens eine Modulationslogikeinheit, die dazu ausgebildet ist, ein dem jeweiligen Schalter zugeordnetes Modulationssignal und das vom jeweiligen Eingangskoppler übertragene Sicherheitsfunktionssignal logisch zu verknüpfen und am Ausgang als freischaltbares Modulationssignal auszugeben.

A first aspect relates to a device for enabling control of a power stage of an electrical machine. The device comprises a first input for detecting or connecting a safety function signal and a second input for detecting or connecting a reference potential of the safety function signal. Furthermore, the device comprises one or at least two switch-off paths for the control. Each switch-off route includes:

• - An input coupler, which is connected on the input side between the first input and the second input and is designed to transmit the safety function signal in a galvanically isolated manner from the inputs;
• - At least one output for driving a switch of a half-bridge of the power stage; and
• - At least one modulation logic unit, which is designed to logically link a modulation signal assigned to the respective switch and the safety function signal transmitted by the respective input coupler and to output it as an unlockable modulation signal at the output.

The unlockable modulation signal can also be referred to as a secure modulation signal.

The modulation logic unit can be a logical operator. Alternatively or additionally, the modulation logic unit can be a logic unit that is designed to logically combine a modulation signal assigned to the respective switch, which is generated by a modulator, and the safety function signal transmitted by the respective input coupler and output it as the modulation signal that can be enabled at the output.

The switch of a half-bridge can be a semiconductor switch.

The device can be a functional safety circuit part for or in a frequency converter.

The electric machine can be an electric motor.

Exemplary embodiments of the device can set the activation of the power stage by means of the modulation logic unit under the condition that the safety function signal is present at the first input and/or at the second input. If there is no safety function signal at the first input and/or at the second input, the or each modulation logic unit outputs the modulation signal assigned to the respective switch of a half-bridge does not respond to the power stage because the transmitted safety function signal has been omitted (ie is not present or is logically equal to zero), ie the power stage is not actuated.

In the same exemplary embodiments or further exemplary embodiments, the or each switch-off path can be configured (e.g. independently of the or the other switch-off paths) to monitor the safety function signal between the inputs (e.g. to be detected by means of the respective input coupler) and in response to the absence of the safety function signal stop driving the power stage (e.g. by means of the modulation logic unit).

The safety function signal can be omitted at the inputs if the first input or the second input is interrupted or potential-free. The safety function signal can be present (for example only present) if a current flows from the first input to the second input. A current representing the safety function signal can flow from the first input through the or each input coupler to the second input.

The input coupler can be designed to transmit the safety function signal represented by a current flowing between the first input and the second input or by a voltage present between the first input and the second input.

The logical link can be a logical AND link (or conjunction) between the associated modulation signal and the transmitted safety function signal.

Because of the AND operation, a (preferably positive) transmitted safety function signal can be a prerequisite for forwarding or transmission or for output of the assigned modulation signal to the power stage.

The device can be designed to enable the driving of N half-bridges (for example for N phases) of the power stage. The device may include at least 2N outputs. A pair of outputs can be assigned to each half-bridge. Each pair of outputs can be designed to drive switches (preferably semiconductor switches, for example a high-side semiconductor switch and a low-side semiconductor switch) of the power stage that are assigned to the respective half-bridge.

The device may comprise at least two switch-off paths, the input couplers of which are connected in series between the first input and the second input.

The safety function signal can be a signal for safe torque interruption (in short: STO signal) of the electrical machine. The STO signal and/or device may be designed according to European Standard IEC 61800-5-2:2007 and/or European Standard 60204 Stop Category 0 or 1.

The electrical machine can be used or can be used as a motor and/or as a generator. The disconnection can (for example in the case of the engine) interrupt a drive torque and/or (for example in the case of the generator) interrupt a braking torque.

The electrical machine can be an electric motor, preferably an asynchronous motor. Alternatively or additionally, the electrical machine can be a three-phase machine.

The device can also include a transformer which is designed to supply a supply voltage, which is galvanically decoupled from a control unit for monitoring the activation and/or a modulator for generating the modulation signal, to the input coupler and/or to the modulation logic unit and/or to the output (e.g output or provide the optocoupler of the output).

A supply voltage of the input coupler or each input coupler and/or a supply voltage of the modulation logic unit or each modulation logic unit can be output or provided independently of the safety function signal (for example independently of the presence or absence of the safety function signal). Alternatively or additionally, a supply voltage of the input coupler or each input coupler and/or a supply voltage of the modulation logic unit or each modulation logic unit can be galvanically decoupled from an operating voltage of a modulator that generates the modulation signal and/or of an output coupler (e.g. an optocoupler) that outputs the modulation signal that can be enabled.

The or each shutdown path may further include a filter. The filter can be connected between the input coupler and the modulation logic unit. The filter may include an amplifier. The amplifier can use the galvanically isolated transmitted safety function signal ver strengthen, for example to a voltage for driving the power stage and / or to a voltage of more than 100 V or more than 200 V. Alternatively or additionally, the filter can include a low-pass filter. The low-pass can filter the amplified safety function signal. Alternatively or additionally, the filter can include a Schmitt trigger. The Schmitt trigger can output the amplified and/or filtered safety function signal with a hysteretic waveform, for example to the modulation logic unit.

A time constant (for example a time characteristic or filter length) of the low-pass filter can be independent of a voltage of the safety function signal.

The or each shutdown route may further include a test logic unit. The test logic unit can be connected between the input coupler and the modulation logic unit. On the input side, the test logic unit can logically link the transmitted safety function signal and a test signal (for example according to an AND link).

The device can also include a control unit (140) which is designed to generate the test signal for interrupting the transmitted safety function signal (e.g. a logic zero) and to monitor a signal profile in response to the test signal at a signal tap on the modulation logic unit or at the output . The control unit can be designed, for example, to issue an instruction to switch off the modulation signal to a modulator that generates the modulation signal if the monitored signal profile does not correspond to the activation of the control in a predetermined time window.

The device may further include a modulator turn-off path. The modulator turn-off path or device may include a modulator generating the modulation signal. The modulator switch-off path can also include an input coupler, which is connected on the input side between the first input and the second input and is designed to transmit the safety function signal electrically isolated from the inputs as a (for example logically inverted) switch-off instruction to the modulator. The modulator can be designed to switch off the modulation signal in response to the transmitted safety function signal being omitted.

The device can also include a modulator which is designed to generate the at least one modulation signal. The transmitted safety function signal can be applied to the modulator in its own switch-off path (the modulator switch-off path). The modulator may be configured to discontinue (i.e., turn off) generation of the at least one modulation signal in response to the cessation (i.e., absence) of the transmitted safety function signal.

The device may further include a controller shutdown path. The controller shutdown path or device may include a controller. The control unit switch-off path can also include an input coupler, which is connected on the input side, for example between the first input and the second input, and is designed to transmit the safety function signal, electrically isolated from the inputs, to the control unit. The control unit can be designed to monitor a signal curve at a signal tap on the modulation logic unit or at the output in response to the absence of the transmitted safety function signal. For example, the control unit can also be designed to issue an instruction to switch off the modulation signal to a modulator that generates the modulation signal if the monitored signal curve does not correspond to the activation of the control in a predetermined time window.

The device can also include a stopping switch-off path (also: braking switch-off path). The holding switch-off path can comprise an electromechanical brake or rotary lock and an input coupler, which is connected on the input side between the first input and the second input and is designed to transmit the safety function signal to the electromechanical brake or rotary lock in a galvanically isolated manner from the first input and from the second input transfer. The electromechanical brake can be designed to generate a braking torque on a shaft of the electrical machine when the transmitted safety function signal is absent, or the electromechanical rotary lock can be designed to generate a holding torque on a shaft of the electrical machine when the transmitted safety function signal is absent.

A second aspect relates to a frequency converter for driving an electric motor. The frequency converter includes a power stage that is designed to switch or generate at least one phase of the electric motor (for example a switch of a half-bridge of the power stage) in accordance with at least one modulation signal that can be enabled. Furthermore, the frequency converter includes a modulator which is designed to generate at least one modulation signal for controlling the power stage. Further includes the frequency converter a device for enabling the control of the power stage according to the first aspect.

According to the first aspect, the device can be designed to logically combine the at least one modulation signal of the modulator with the transmitted safety function signal in order to output the modulation signal that can be activated.

Here, the term frequency converter also includes an inverter with a variable frequency (for example in accordance with the at least one modulation signal). Depending on the number of phases switched by the power stage, the inverter can be a single-phase, two-phase, three-phase or multi-phase inverter.

The frequency converter can be operated with direct current or alternating current. For example, the power stage can have or can have a DC voltage applied to it as the supply voltage on the input side. Alternatively or additionally, the frequency converter can include a rectifier (for example an intermediate circuit with a rectifier) to which an AC voltage is or can be applied as the supply voltage on the input side. On the output side, the rectifier (or the intermediate circuit) can be electrically connected to the input of the power stage.

The frequency converter can be a variable speed starter or can be integrated into a variable speed starter. The control unit can also be designed to control the modulator according to a starting method of the electric motor and/or to control the modulator to reverse the electric motor.

The invention is explained in more detail below with reference to the drawings using preferred exemplary embodiments.

• 1 ein schematisches Blockschaltbild einer Vorrichtung zur Freischaltung einer Ansteuerung einer Leistungsstufe und eines entsprechenden Frequenzumrichters gemäß einem ersten Ausführungsbeispiel;
• 2 ein schematisches Blockschaltbild einer Vorrichtung zur Freischaltung einer Ansteuerung einer Leistungsstufe und eines entsprechenden Frequenzumrichters gemäß einem zweiten Ausführungsbeispiel;
• 3 ein schematisches Blockschaltbild einer Vorrichtung zur Freischaltung einer Ansteuerung einer Leistungsstufe und eines entsprechenden Frequenzumrichters gemäß einem dritten Ausführungsbeispiel;

Show it:

• 1 a schematic block diagram of a device for enabling a control of a power stage and a corresponding frequency converter according to a first embodiment;
• 2 a schematic block diagram of a device for enabling a control of a power stage and a corresponding frequency converter according to a second embodiment;
• 3 a schematic block diagram of a device for enabling a control of a power stage and a corresponding frequency converter according to a third embodiment;

1 1 shows a schematic block diagram of a first exemplary embodiment of a device, denoted generally by reference numeral 100, for enabling control of a power stage, denoted generally by reference numeral 200. The power stage 200 can be designed or used to drive or to collect current from an electrical machine, which is generally designated by reference numeral 300, ie an electric motor or an electric generator.

The first exemplary embodiment of the device 100 includes a first input 102 for detecting a safety function signal and a second input 104 for detecting a reference potential of the safety function signal. Furthermore, in the case of the first exemplary embodiment, the device 100 comprises a switch-off path 106 of the control. Other embodiments may include two or more shutdown paths 106 .

Each switch-off path 106 includes an input coupler 110. The input coupler 110 is connected between the first input 102 and the second input 104 on the input side. The input coupler 110 is designed to transmit the safety function signal in a galvanically isolated manner from the first input 102 and from the second input 104 .

Furthermore, each switch-off path 106 comprises at least one output 130 for driving a switch of a half-bridge of the power stage 200 (e.g. a phase of the power stage 200), preferably for driving a positive or negative section of the phase and/or a semiconductor switch (e.g. an IGBT) on the high-side branch or on the low-side branch of power stage 200.

Each switch-off path 106 also includes a modulation logic unit 120, which is designed to logically combine a modulation signal 166 assigned to the respective switch (e.g. the positive or negative section of the phase) and the safety function signal transmitted by the respective input coupler 110, and at the output as a modulation signal 108 that can be enabled to spend The modulation signal preferably has two logic levels and/or corresponds to a pulse width modulation (PWM).

If the safety function signal is absent, a supply voltage of the input coupler 110 and/or the modulation logic unit 120 is preferably not controlled or not interrupted. As an alternative or in addition, the failure of the supply voltage in each switch-off path 106 can have the same effect as the transmitted safety function signal is no longer available, ie the actuation is enabled if the supply voltage fails.

In each exemplary embodiment, the one or at least two shutdown paths 106 can implement a safe torque interruption (i.e., a "Safe Torque Off" or STO function).

In each embodiment, the output 130 may include an output coupler for galvanically isolated transmission of the modulation signal 108 that can be enabled to the power stage 200 . The output coupler may include an optocoupler.

While the first exemplary embodiment includes a switch-off path 106, further exemplary embodiments, for example in a further development of the first exemplary embodiment, can have two or more switch-off paths 106.

In a further exemplary embodiment, the device 100 for driving a power stage 300 for single-phase alternating current can include two switch-off paths 106 for the upper (technically also: "high-side") and lower (technically also: "low-side") branch of a half-bridge. Optionally, a third switch-off path can be provided for a microcontroller that monitors or tests the device.

In yet another exemplary embodiment, the device 100 for controlling a power stage 300 for three-phase current has six switch-off paths 106 for the upper (technically also: "high-side") and lower (technically also: "low-side") branch of three half-bridges each (technically also: B6 bridge). Optionally, a seventh switch-off path can be provided for a microcontroller that monitors or tests the device.

In each exemplary embodiment, one or at least two separate switch-off paths 106 can be provided in order to implement an STO function, for example in a variable-speed starter of electric motor 300 .

A “STO+” signal (for example with a nominal voltage of 24 V) can be detected and/or connected to the first input 102 . At the second input 104, an associated reference potential or reference potential, i.e. an "STO" signal (for example with a nominal voltage of 0 V) can be recorded and/or connected. If one of the two signals fails (e.g. if the corresponding input becomes potential-free or an electrical connection of the corresponding input becomes high-impedance), then the transmitted safety function signal is lost in each switch-off path, i.e. the safety function is triggered.

In the input coupler 110, these two signals, STO+ and STO-, are each electrically isolated from the respective switch-off path 106 by means of an optocoupler 110. The switch-off path or paths 106 can also be referred to as a channel or channels.

The power stage 200 will be powered from a positive terminal 202 (DC+) and a negative terminal 204 (DC-) of a DC voltage (e.g. a DC mains or a rectified voltage). The power stage switches the DC voltage according to the modulation signal 166 to generate the corresponding (i.e. the modulation signal 166 assigned) phase for the electric machine 300.

The device 100 can be implemented as a circuit part of the functional safety, preferably as a circuit part of the safety function STO.

Furthermore, the 1 a schematic block diagram of a first exemplary embodiment of a frequency converter, generally designated by reference numeral 400, for driving an electric motor 300.

The first exemplary embodiment of the frequency converter 400 comprises a power stage 200 which is designed to switch or generate at least one phase of the electric motor 300 in accordance with at least one modulation signal 108 which can be activated. For this purpose, the power stage 200 can include a semiconductor bridge with two switches (for example semiconductor switches) per phase. Furthermore, the frequency converter 400 includes a modulator 160 which is designed to generate at least one modulation signal 166 for driving the at least one semiconductor bridge (for example the respective switch of the semiconductor bridge) of the power stage 200 . Frequency converter 400 also includes a device 100 for enabling the control of power stage 200 according to one of the exemplary embodiments described herein, wherein device 100 logically combines the at least one modulation signal 166 of modulator 160 with the transmitted safety function signal in order to output the modulation signal 108 that can be enabled for the respective phase (e.g. the respective Power stage semiconductor bridge switch 200).

Each exemplary embodiment of the device 100 and/or the frequency converter 400 can comprise a transformer 150 (for example a DC/DC converter) with galvanic isolation. For example, the transformer 150 has a first galvanically isolated output 152, at which the transformer 150 provides a supply voltage for the device 100, preferably for the input coupler 110 and/or for the modulation logic unit 120 and/or the output 130.

An optional second decoupled output 154 of the transformer 150 provides the supply voltage of the output 130 and/or an operating voltage at the inputs 162 and 164 of the modulator 160 and/or an operating voltage of a control unit (for example a microcontroller) of the device 100.

The control is preferably enabled exclusively via the switch-off path(s) 106 (or one of the other switch-off paths 107A and/or 107B), while the supply and operating voltages of the other components of the device 100 and/or the frequency converter 400 are not controlled, for example not interrupted , become when the safety function signal is omitted.

Electrical drives must fulfill safety functions. Embodiments of the device 100 or the frequency converter 400 can implement a safety function for torque interruption (technically also referred to as "Safe Torque Off" or STO) by the power stage being controlled by the modulation signal 108 that can be enabled (for example with a voltage of 0 V), to immediately interrupt a power supply of the electric motor 300 as a drive. The safety function "STO" of the frequency converter 400 controlling the drive 300 can interrupt the current and thus the torque of the drive.

The drive 300 can no longer generate any torque after the STO has been switched off by means of the device 100 or the frequency converter 400 . With the interruption of the current, a torque of the drive 300 can be eliminated with immediate effect and the drive 300 can be stopped uncontrolled.

The STO safety function can correspond to stop category 0 of the European standard EN 60204.

Since the drive 300 can no longer generate a braking torque electrically when the STO is switched off, separate measures such as a mechanical brake are advantageous for braking the drive 300, for example so that there is no undesired overrun or end positions are not exceeded. When external forces act (such as a raised mass or spring forces), a mechanical brake or a mechanical lock can be designed to generate a braking torque or a holding torque for a shaft of electric motor 300 in response to the absence of the safety function signal, preferably around the to prevent possible position change in a torque-free drive 300.

For example, the device 100 may include a hold-off path. The hold-turn-off path includes an input coupler 110. The input coupler 110 is connected between the first input 102 and the second input 104 on the input side. The input coupler 110 is designed to transmit the safety function signal, electrically isolated from the first input 102 and from the second input 104, to an electromechanical brake or rotary lock. If the transmitted safety function signal is omitted, the brake generates the braking torque or the rotary lock generates the holding torque on a shaft of electrical machine 300.

In each embodiment, electric machine 300 may be an electric motor. The electric motor 300 can be a three-phase asynchronous motor, for example with a power consumption of 50 W to 3 kW.

2 shows a schematic block diagram of the device 100 and a corresponding frequency converter 400 according to a second embodiment. The second exemplary embodiment can be implemented on its own or as a further development of one of the aforementioned exemplary embodiments, for example the first exemplary embodiment.

The second exemplary embodiment comprises at least two switch-off paths 106, for example two switch-off paths for each phase generated by the power stage 200 for driving the electric motor 300 or two switch-off paths for all (for example three) phases generated by the power stage 200 for driving the electric motor 300. As a modulation signal 166 For the at least one modulation logic unit 120 of the first switch-off path 106 (e.g. per phase), the modulator 160 generates a pulse-width-modulated signal 166 to generate the phase section of positive voltage (e.g. positive with respect to a time-averaged voltage of the respective phase) or to control an upper (also : high side) Branch of a half-bridge for generating the respective phase in power stage 200. Modulator 160 also generates, as modulation signal 168 of the at least one modulation logic unit 120 of second turn-off path 106 (e.g. per phase), a pulse-width-modulated signal 168 for generating the phase section of negative voltage (e.g with regard to a time-averaged voltage of the respective phase) or to control a lower (also: low-side) branch of the half-bridge for generating the respective phase in the power stage 200.

In each exemplary embodiment, the inputs 102 and/or 104 can be compatible with test pulses from safety switching devices. For example, the test pulses are filtered out, preferably in each switch-off path 106 (and possibly in each of the other switch-off paths 107A and/or 107B). Exemplary embodiments of the device 100 and/or the frequency converter 400 can be designed for both positive and negative test pulses. A filter time for filtering out the test pulses is preferably independent of a voltage level at inputs 102 and/or 104.

Preferably, the device 100 includes at least one modulator shutdown path 107A. Each modulator shutdown path 107A includes an input coupler 110. The input coupler 110 is connected on the input side between the first input 102 and the second input 104, for example in series with the input couplers 110 of the shutdown paths 106. The input coupler 110 of the modulator shutdown path 107A is designed for this purpose to transmit the safety function signal electrically isolated from the first input 102 and from the second input 104 as a (for example logically inverted) switch-off instruction 142 for switching off the modulation signals 166 and 168 to the modulator 160. The device 100, for example the modulator disable path 107A, may include the modulator 160 controlled by the transmitted safety function signal.

3 shows a schematic block diagram of the device 100 and a corresponding frequency converter 400 according to a third exemplary embodiment. The third exemplary embodiment can be implemented on its own or as a further development of one of the aforementioned exemplary embodiments, for example the first and/or second exemplary embodiment.

Each shutdown path 106 preferably includes a filter 122, for example a low-pass filter 122. Within the respective shutdown path 106, the filter 122 can be connected between the input coupler 110 and the modulation logic unit 120, for example between a test logic unit 121 and the modulation logic unit 120.

The galvanic isolation by means of the respective input coupler 110 makes it possible to implement the switch-off path(s) 106 on the potential of driving the power stage 200 that is dangerous to touch. As a result, the device 100 can use a microcontroller 140 located at this potential for diagnostic purposes and/or in a microcontroller shutdown path 107B (for example in a third shutdown path or in a further shutdown path). For example, the transmitted safety function signal can be represented within the shutdown path 106 by a voltage of more than 100V.

The filter 122 may include an amplifier 124 configured to amplify the transmitted safety function signal to the potential of the power stage 200 drive.

Alternatively or additionally, the filter 122 can include a low-pass filter 126 and/or a Schmitt trigger 128, preferably an inverting Schmitt trigger 128.

If the safety function signal is omitted with the in 3 The third exemplary embodiment shown does not forward a first switch-off path 106 to a first PWM signal (as a first modulation signal 166) from the modulator 160 (as a high-side driver). A second switch-off path 106 does not forward a second PWM signal (as a second modulation signal 168) from the modulator 160 (as a low-side driver).

Each embodiment of the device 100 may further comprise a microcontroller shutdown path 107B, for example as a third shutdown path and/or as schematically shown in FIG 3 shown. The microcontroller shutdown path 107B includes an input coupler 110. The input coupler 110 is connected on the input side between the first input 102 and the second input 104, for example in series with the input couplers 110 of the shutdown paths 106 and/or the input coupler 110 of the shutdown path 107A.

The input coupler 110 of the microcontroller shutdown path 107B is designed to transmit the safety function signal electrically isolated from the first input 102 and from the second input 104 to a microcontroller 140 of the shutdown path 107B of the device 100 .

The microcontroller 140 can be designed to check, in response to the absence of the safety function signal, at a signal tap at the output 130 of each switch-off path 106 whether the modulation signal that can be enabled is actually off is switched, for example set to 0V or DC.

Alternatively or additionally, microcontroller 140 is configured to, in response to the absence of the safety function signal, issue a switch-off instruction 142 to switch off the modulation signal to modulator 160, for example to transmit a switch-off instruction 142 to switch off modulation signals 166 and 168 to modulator 160. For example, microcontroller 140 turns PWM signals 166 and 168 off.

The device 100, for example the modulator disable path 107A, may include the modulator 160 controlled by the transmitted safety function signal. Alternatively or additionally, the modulator 160 can be arranged in the frequency converter 400 outside the device 100 .

In each exemplary embodiment, in order to ensure that the operational functions for functional safety (e.g. the functions of device 100) are non-reactive, all signals (e.g. the transmitted safety function signal and/or the modulation signal 166 or 168 of the modulator 160 and/or the modulation signal 108 that can be activated ) and/or and the supply voltage of the first output 152 of the transformer 150 and/or the operating voltage of the second output 154 of the transformer 150 can be decoupled from one another.

In each exemplary embodiment, to check the switching capability (e.g. of the modulation logic unit 120 and/or the Schmitt trigger 128) and/or the temporal behavior of the individual shutdown paths 106 (e.g. a time constant of the filter 122, preferably of the low-pass filter 124) in one or each shutdown path 106 a test logic unit 121 can be installed as a test switch.

In each shutdown path 106, a test logic unit 121 can be connected between the input coupler 110 and the modulation logic unit 120, for example between the input coupler 110 and the filter 122. Test logic unit 121 can be designed to logically link the modulation signal transmitted by input coupler 110 and a test signal 144, for example according to an AND operation, and to output this in shutdown path 106, for example to filter 122 or to modulation logic unit 120.

The device 100 can include a control unit 140, for example the aforementioned microcontroller 140, for checking the switching capability and/or the behavior over time.

The control unit 140 can be designed to use a test signal 144 (for example a logic zero) to simulate the absence of the safety function signal in the respective switch-off path 106 . The control unit 140 can also be designed to detect (for example scan) a voltage profile of the transmitted safety function signal at a signal tap 129 in the respective switch-off path 106 between the test logic unit 121 and the modulation logic unit 120 . If the transmitted safety function signal is omitted at the signal tap 129 within a predetermined time window after the output of the test signal 144 for simulating the omitted safety function signal, the result of the check is an operating state of the device 100. Otherwise the result of the check is an error state. In the error state, control unit 140 can output the error state (e.g. output optically and/or acoustically) and/or output switch-off instruction 142 to switch off modulation signal 166 and/or 168 to modulator 160 (preferably regardless of whether the safety function signal at inputs 102 and 104 is applied or has been omitted).

Alternatively or additionally, the control unit 140 (for example the aforementioned microcontroller 140) of the device 100 can be designed to carry out at least one of the following control functions. A first control function is starting the motor 300, preferably as a soft start (technically also: soft start) with power limitation when the motor 300 is switched on. A second control function is reversing the motor 300.

In each exemplary embodiment, the modulation logic unit 120 and/or the test logic unit 121 can include at least one logic gate (preferably an AND element) to implement the respective logic operation (for example a corresponding Boolean operation).

In the representation of 3 only the switch-off paths 106 to two switches of a half-bridge of the power stage 200 are drawn in for the sake of clarity. One output coupler 130 (such as an optocoupler) is required for each switch. For example, in the case of a three-phase asynchronous machine, a total of six output couplers 130 (e.g. optocouplers) and six modulation logic units 120 are required as the electrical machine 300 (ie three phases, each of which is controlled by a half-bridge with two switches). modulation signal from three modulation signals 166 and three modulation signals 168. The six output couplers 130 output six modulation signals 108 which can be enabled.

In a first variant of each exemplary embodiment, the AND elements 120 (and above them the output couplers 130) for different switches of the half bridges can be connected to the same input coupler 110 or to the same test logic unit 121 or to the same filter 122. That is, one or each of the shutdown paths 106 may include more than one output coupler 130. In a second variant of each exemplary embodiment, which can be combined with the first variant for different switch-off paths 106, different switches of the half-bridges can each be connected to their own switch-off paths 106. For example, the device 100 may include more than two shutdown paths 106 .

The device 100 can be provided or used as a safety function of the frequency converter 400 . Alternatively or additionally, the device 100 can bring about a current interruption in the control of the frequency converter 400 .

Although the invention has been described with reference to exemplary embodiments, those skilled in the art will recognize that various changes may be made and equivalents may be substituted. Furthermore, many modifications can be made to adapt a particular situation or material to the teachings of the invention. Accordingly, the invention is not limited to the disclosed embodiments, but includes all embodiments falling within the scope of the appended claims.

Reference List

100

Device for enabling control of a power stage

102

First input of a safety function signal, preferably an STO signal

104

Second input of a reference potential for the safety function signal

106

switch-off way

107A

Modulator Shutdown Path

107B

Control unit shutdown path, preferably microcontroller shutdown path

108

Unlockable modulation signal

110

Electrically isolating input coupler of the safety function signal, e.g. optocoupler

120

Modulation logic unit, such as AND gate

121

Test logic unit, for example AND gate

122

Filters, such as low-pass filters

124

amplifier

126

low pass

128

Schmitt trigger, preferably inverting Schmitt trigger

129

Signal tap for diagnosis

130

Output of the modulation signal that can be activated, preferably a galvanically isolating output coupler, for example an optocoupler

140

Control unit, for example monitoring of the safety function

142

Instruction to switch off the modulation signals

144

test signal

150

Decoupling transformer, e.g. galvanically isolated DC/DC converter

152

First decoupled output of the transformer

154

Second decoupled output of the transformer

160

Modulator, e.g. microcontroller or clock generator for PWM signal

162

Operating signal input

164

Input of the reference potential to the operating signal First modulation signal,

166

for example PWM signal for positive phase section and/or for semiconductor switches of a high-side branch

168

Second modulation signal, for example PWM signal for negative phase section and/or for semiconductor switches of a low-side branch

200

Power stage, for example half-bridge, H-bridge or B6-bridge

202

First mains connection, for example positive connection to the DC voltage mains

204

Second mains connection, for example negative connection to the DC voltage mains

300

Electrical machine, preferably three-phase asynchronous machine

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 102011003922 A1 [0002]

Claims (15)

Device (100) for enabling activation of a power stage (200) of an electrical machine (300), comprising: a first input (102) for detecting a safety function signal and a second input (104) for detecting a reference potential of the safety function signal; and one or at least two switch-off paths (106) of the control, each switch-off path (106) comprising in each case - an input coupler (110), which is connected on the input side between the first input (102) and the second input (104) and is designed to transmit the safety function signal in a galvanically isolated manner from the inputs (102, 104); - At least one output (130) for driving a switch of a half-bridge of the power stage (200); and - at least one modulation logic unit (120), which is designed to logically combine a modulation signal (166; 168) assigned to the respective switch and the safety function signal transmitted by the respective input coupler (110) and to output it as an unlockable modulation signal (108) at the output (130). . Device (100) according to claim 1 , wherein the logical link is a logical AND link between the assigned modulation signal (166; 168) and the transmitted safety function signal. Device (100) according to claim 1 or 2 , wherein the device (100) is designed to enable the activation of N half-bridges of the power stage (200), wherein the device (100) comprises at least 2.N outputs (130), and each half-bridge of the power stage (200) has a pair associated with the outputs (130). Device (100) according to one of Claims 1 until 3 , the device comprising at least two switch-off paths (106; 107A; 107B) whose input couplers (110) are connected in series between the first input (102) and the second input (104). Device (100) according to one of Claims 1 until 4 , wherein the safety function signal is a signal for safe torque interruption, STO signal, of the electrical machine (300), preferably according to European standard IEC 61800-5-2:2007 and/or stop category 0 or 1 of European standard 60204. Device (100) according to one of Claims 1 until 5 , wherein the electrical machine (300) is an electric motor, preferably an asynchronous motor. Device (100) according to one of Claims 1 until 6 , further comprising: a transformer (150) which is designed to supply a supply voltage (152) galvanically decoupled from a control unit (140) for monitoring the activation or a modulator (160) for generating the modulation signal (166; 168) to the input coupler (110) and/or to the modulation logic unit (120) and/or to the output (130). Device (100) according to one of Claims 1 until 7 , wherein a supply voltage (152) of the input coupler (110) or the input coupler (110) and/or a supply voltage (152) of the modulation logic unit (120) or the modulation logic units (120) is output independently of the safety function signal, and/or wherein a supply voltage ( 152) of the input coupler (110) or the input coupler (110) and/or a supply voltage (152) of the modulation logic unit (120) or the modulation logic units (120) is galvanically decoupled from an operating voltage (154) of one generating the modulation signal (166; 168). Modulator (160) and/or an output coupler which outputs the modulation signal (108) which can be activated at the output (130). Device (100) according to one of Claims 1 until 8th wherein the or each shutdown path (106) further comprises a filter (122) connected between the input coupler (110) and the modulation logic unit (120). Device (100) according to claim 9 wherein the filter (122) comprises: an amplifier (124); and/or a low-pass filter (126); and/or a Schmitt trigger (128). Device (100) according to one of Claims 1 until 10 , wherein the or each switch-off path (106) further comprises a test logic unit (121) which is connected between the input coupler (110) and the modulation logic unit (120) and on the input side logically combines the transmitted safety function signal and a test signal (144), and wherein the device (100) further comprises a control unit (140) which is designed to generate the test signal (144) for interrupting the transmitted safety function signal and in response to the test signal (144) at a signal tap (129) on the modulation logic unit (120) or at the output (130) a waveform too monitors, preferably wherein the control unit (140) is also designed to output an instruction (142) to switch off the modulation signal (166; 168) to a modulator (160) that generates the modulation signal (166; 168) if the monitored signal profile is not in corresponds to a predetermined time window for activation of the control. Device (100) according to one of Claims 1 until 11 , further comprising a modulator switch-off path (107A), wherein the modulator switch-off path (107A) comprises a modulator (160) generating the modulation signal (166; 168) and an input coupler (110) which is connected on the input side between the first input (102) and is connected to the second input (104) and is designed to transmit the safety function signal electrically isolated from the inputs (102, 104) as a switch-off instruction (142) to the modulator (160), the modulator (160) being designed to, in Switching off the modulation signal (166; 168) in response to a failure of the transmitted safety function signal. Device (100) according to one of Claims 1 until 12 , further comprising a controller shutdown path (107B), wherein the controller shutdown path (107B) comprises a controller (140) and an input coupler (110) connected on the input side between the first input (102) and the second input (104). and is designed to transmit the safety function signal electrically isolated from the inputs (102, 104) to the control unit (140), wherein the control unit (140) is designed to, in response to the absence of the transmitted safety function signal, a signal curve at a signal tap ( 129) at the modulation logic unit (120) or at the output (130), preferably wherein the control unit (140) is also designed to send an instruction (142) to switch off the modulation signal (166; 168) to a modulation signal (166; 168) generating modulator (160) if the monitored signal curve is not within a predetermined time window of activation of the control e corresponds to Device (100) according to one of Claims 1 until 13 , further comprising a holding switch-off path, wherein the holding switch-off path comprises an electromechanical brake or rotary lock and an input coupler (110) which is connected on the input side between the first input (102) and the second input (104) and is designed to to transmit a safety function signal electrically isolated from the first input (102) and from the second input (104) to the electromechanical brake or rotary lock, the electromechanical brake being designed to apply a braking torque to a shaft of the electrical machine (300) if the transmitted safety function signal is lost generate, or the electromechanical rotary lock is designed to generate a holding torque on a shaft of the electrical machine (300) when the transmitted safety function signal is omitted. Frequency converter (400) for driving an electric motor (300), comprising: a power stage (200) which is designed to switch at least one phase of the electric motor (300) in accordance with at least one modulation signal (108) which can be activated; a modulator (160) which is designed to generate at least one modulation signal (166; 168) for driving the power stage (200); and a device (100) for enabling the control of the power stage (200) according to one of Claims 1 until 14 , wherein the device (100) logically combines the at least one modulation signal (166; 168) of the modulator (160) with the transmitted safety function signal in order to output the modulation signal (108) that can be activated.

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