Abstract:
The invention relates to a control device for controlling an electronically commutated motor. The control device comprises a control input for a rotor position signal and a control output for connection to field coils of the motor. The control device is designed to generate a load current for displacing a rotor of the motor depending on the rotor position signal and to output said load current via the control output. The control device comprises at least one semiconductor switch for switching the load current depending on a semiconductor control signal. The control device comprises at least one pulse generator including the at least one semiconductor switch, said pulse generator being designed to generate the load current in the form of a pulsed control signal for displacing the rotor. The control device is characterized by a delta sigma converter which is at least indirectly connected to the control input on the input side and which is designed to produce the semiconductor control signal in the form of a digital bit stream depending on the rotor position signal.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a control device for controlling an electronically commutated motor. The control device has a control input for a rotor position signal and a control output for connection to field coils of the motor, the rotor position signal representing a rotor position of a rotor of the motor. The control device is designed to generate a load current, in particular a torque, for moving the rotor on the basis of the rotor position signal and to output said load current via the control output. The control device has at least one semiconductor switch which is connected to the control output and is designed to switch the load current for moving the rotor on the basis of a semiconductor control signal. 
         [0002]    DE 103 59 71 33 A1 discloses a rotor position sensor arrangement and a method for detecting a rotor position, in which a ferromagnetic rotor of a motor has sensor magnets for generating a rotor signal. The rotor position sensor arrangement also has a rotor position evaluation device which is designed to generate a rotor position signal which represents a digital value with a resolution of at least 2 bits. The rotor position evaluation device also has an analog/digital converter with a resolution of at least 2 bits. 
       SUMMARY OF THE INVENTION 
       [0003]    The control device according to the invention has the features of the control device of the type mentioned at the outset, the control device, in particular the pulse generator, having a delta sigma converter. The delta sigma converter is at least indirectly connected, on the input side, to the control input and is designed to generate the semiconductor control signal in the form of a digital bit stream on the basis of the rotor position signal. This advantageously makes it possible for the load current to be formed as a pulsed control signal, in particular as a pulsed load current, which represents the bit stream. 
         [0004]    As a result of the delta sigma converter, the control signal can be advantageously generated with a high resolution by the delta sigma converter. Furthermore, the semiconductor control signal can be advantageously generated with a high signal-to-noise ratio, for example with 60-fold oversampling. Furthermore, the delta sigma converter can be advantageously used to process the rotor position signal with a high degree of accuracy in order to generate the control signal for moving the rotor. 
         [0005]    The at least one semiconductor switch is preferably in the form of a transistor in a transistor half bridge or full bridge. The semiconductor control signal for this embodiment is also referred to as a transistor control signal below. The transistors may each be in the form of a MOS-FET (MOS-FET=Metal Oxide Semiconductor Field Effect Transistor), a MIS-FET (MIS=Metal Insulator Semiconductor), a bipolar transistor, a JFET (JFET=Junction FET), an IGBT (IGBT=Insulated Gate Bipolar Transistor), an HEMT (HEMT=High Electron Mobility Transistor), an HBT (HBT=Heterojunction Bipolar Transistor) or the like, for example. 
         [0006]    In another embodiment, the at least one semiconductor switch may also be in the form of a thyristor or a triac, for example, which switches the load current on the basis of the semiconductor control signal. 
         [0007]    The control device preferably has at least one pulse generator which comprises the at least one semiconductor switch and is operatively connected, on the input side, to the control input and is connected, on the output side, to the control output. The pulse generator is designed to generate the load current for moving the rotor in the form of a pulsed control signal such that the pulsed control signal has temporally successive pulses with a respective control pulse duration and also preferably pulse pauses with a respective pulse pause duration. 
         [0008]    The delta sigma converter is implemented, for example, by a DSP (DSP=Digital Signal Processor), an FPGA (FPGA=Field Programmable Gate Array), a microprocessor, in particular in conjunction with a program stored on a computer program product, or by a microcontroller. 
         [0009]    In one advantageous embodiment of the control device, the delta sigma converter has a noise generator, in particular a digital noise generator, which is designed to generate the digital bit stream by superimposing noise, in particular by means of quantization and discretization. 
         [0010]    The noise generator is preferably formed by virtue of the fact that the delta sigma converter does not have a low-pass filter on the output side. A low-pass filter on the output side is advantageously preferably formed by a load which is connected to the pulse generator on the output side and has an impedance with a low-pass characteristic. The load is also preferably formed by the field coils. This advantageously makes it possible to increase a pulse repetition frequency bandwidth of the control signal in comparison with a frequency bandwidth of the rotor position signal received on the input side. 
         [0011]    For example, the delta sigma converter has an IIR filter (IIR=Infinite Impulse Response). The noise generator preferably has a predetermined noise power which is determined by an order of the IIR filter. The IIR filter may be formed as a second-order filter or as a filter with an order greater than the second order. This advantageously makes it possible to set a noise power of the noise generator on the basis of the order. 
         [0012]    The noise generator is preferably designed to superimpose white noise, in particular, on a rotor control signal which is received on the input side and was generated on the basis of the rotor position signal. In another embodiment, the noise generator may be designed to superimpose colored noise, in particular pink noise, on the rotor control signal which is received on the input side and was generated on the basis of the rotor position signal. As a result of the superimposition of pink noise, low frequencies in comparison with high frequencies of the pink noise advantageously have a higher energy density than the high frequencies. The noise generator advantageously causes the frequency bandwidth of the rotor position signal received on the input side and/or of the rotor control signal to be wider than that without a noise generator. As a result, interference power in the control signal is advantageously distributed to frequencies which are different from one another and a better control signal, in terms of electromagnetic compatibility, than with conventional pulse width modulation is thus generated overall as the end result. 
         [0013]    The control device preferably has a rotor control unit which is designed to generate the rotor control signal—in particular in the form of an analog voltage signal—on the basis of the rotor position signal. The pulse generator is preferably designed to use the rotor position signal to generate a discrete pulsed control signal representing the bit stream. 
         [0014]    In one preferred embodiment, the control device has a subtraction element which is operatively connected to the control input on the input side. The subtraction element is connected to a voltage feedback means. The voltage feedback means connects a load branch of the semiconductor switch, in particular of the transistor half bridge or full bridge, to the subtraction element and is designed to feed back a voltage from the load circuit to the subtraction element, thus forming a control element, in particular comprising the voltage feedback means and the subtraction element. The control element is designed to compensate for a supply voltage fluctuation at least partially or completely. As a result of the control element, the control signal for driving the field coils of the motor may advantageously not have the supply voltage fluctuation or may only partially have the supply voltage fluctuation. 
         [0015]    In one preferred embodiment, the voltage feedback means has a voltage divider which is connected to the control output and to a ground connection. A dividing connection of the voltage divider is connected to the subtraction element. The voltage divider may thus feed back a potential generated between the ground connection and the control output using voltage division to the subtraction element. The voltage feedback means formed in this manner advantageously makes it possible to feed back a supply voltage fluctuation, which would be present in the output signal without the voltage feedback means, to the subtraction element and thus to advantageously compensate for said fluctuation at least partially or completely. 
         [0016]    In one preferred embodiment, the control element has an analog/digital converter which is connected to the load branch on the input side, the analog/digital converter being at least indirectly connected to the subtraction element on the output side and being designed to generate a bit stream which represents a supply voltage of the control device. The digital voltage feedback means formed in this manner advantageously makes it possible to calculate a value of the supply voltage at the input of the delta sigma converter by means of subtraction. 
         [0017]    In one advantageous embodiment, the control element has a digital/digital converter which is connected to the analog/digital converter on the output side, the digital/digital converter being connected, on the output side, to the subtraction element and being connected, on the input side, to the analog/digital converter. The digital/digital converter is preferably a 1-bit digital/digital converter. The digital/digital converter preferably has a control input which is connected to the digital bit stream generated by the delta sigma converter. If there is a logic “one” of the bit stream at the control input, the digital/digital converter is designed to digitally convert a digital signal from the analog/digital converter that is received at the signal input and to output a conversion result or a previously generated conversion result on the output side. If a signal which represents a logic “zero” of the bit stream is received at the control input on the input side, the digital/digital converter is designed to generate an output signal which corresponds to the logic “zero” or to generate no output signal. The digital/digital converter advantageously makes it possible to precisely compensate for a supply voltage fluctuation. 
         [0018]    The invention also relates to a motor having a control device of the type described above. The motor has a rotor in the form of a permanent magnet and a stator with at least two field coils. The field coils are connected to the control output of the control device. 
         [0019]    In one preferred embodiment, the stator of the motor has three field coils, and the control device has a 3H or B6 bridge consisting of a plurality of semiconductor switches in order to drive the field coils, the semiconductor switches preferably being in the form of transistors. In this context, the B6 bridge consists of three transistor half bridges and the 3H bridge consists of three transistor full bridges or six transistor half bridges. In the case of an H bridge, a first connection of a field coil is connected to an output of one transistor half bridge and another connection of the field coil is connected to an output of a second transistor half bridge. In the case of a B6 bridge, an output of one transistor half bridge is connected to one connection of a field coil, and a second connection of the field coil is connected—depending on the connection of the field coils—to the second connections of the other field coils in the case of a star connection and to a first connection of another field coil in the case of a delta connection. 
         [0020]    The motor having the control device described above advantageously has a noise generation and/or emission spectrum which, in the case of a corresponding design of the delta sigma converter, has a frequency distribution which is psychoacoustically favorable for human hearing and in which, for example, frequency components of the noise generation spectrum are outside a frequency range that can be perceived by a human ear and/or are distributed, in terms of energy, over a frequency range in such a manner that tonal components of the noise generation spectrum advantageously cause less interference. 
         [0021]    For example, a sampling frequency of the delta sigma converter is twenty times, preferably 50 times or 100 times a rotor rotational frequency of the rotor. 
         [0022]    The invention also relates to a method for generating a torque using a rotor of an electronically commutated motor. In the method, a control signal for moving the rotor is generated on the basis of a rotor position signal representing a rotor position of the rotor, the control signal having control pulses and pulse pauses. The control signal is preferably generated using delta sigma conversion. 
         [0023]    In one preferred embodiment of the method, a pulse repetition frequency bandwidth of the control signal is increased in comparison with a frequency bandwidth of the rotor position signal received on the input side. As a result, a noise emission spectrum of an electronically commutated motor operated using the method can be advantageously configured in a psychoacoustically favorable manner. 
         [0024]    In a further preferred embodiment of the method, the rotor of the electronically commutated motor is moved using the pulsed control signal and a torque is thus generated, in particular. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The invention is now explained below using further advantageous exemplary embodiments and using figures. 
           [0026]      FIG. 1  schematically shows an exemplary embodiment of an electronically commutated motor having a control device with a delta sigma converter; 
           [0027]      FIG. 2  schematically shows an exemplary embodiment of a control device for an electronically commutated motor with a delta sigma converter; 
           [0028]      FIG. 3  shows an exemplary embodiment of signal sequences which are each detected at different locations of a signal path inside the control device; 
           [0029]      FIG. 4  schematically shows an exemplary embodiment of a method for controlling an electronically commutated motor. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1  schematically shows an exemplary embodiment of an electronically commutated motor  3  having a control device  1 . The motor  3  has a rotor  5  which is rotatably mounted around a shaft  41 . The control device  1  has a control input  7  and a control output  9 . The control device  1  also has a pulse generator  10  having an input  8  for a rotor control signal. The pulse generator  10  is connected, on the output side, to the control output  9 . The control output  9  of the control device  1  is connected to a connection of a field coil  11 . In addition to the field coil  11 , the motor  3  has a field coil  13  and a field coil  15  which, respectively held by a stator  43 , are each arranged at an angle of 120° in the circumferential direction of the rotor  5  at a predetermined radial distance from the shaft  41 . The control unit  1  is associated with the field coil  11 , a pulse generator  44  of the motor  3  is associated with the field coil  13  and a pulse generator  45  of the motor  3  is associated with the field coil  15 . The pulse generators  44  and  45  are each designed like the pulse generator  10 . 
         [0031]    The control device  1  has a subtraction element  22 , a positive input of which is connected, on the input side, to the input  8  of the pulse generator  10  and is operatively connected to the control input  7  via a control unit  42 . The subtraction element  22  is connected, on the output side, to an adding element  24  via a connecting line  55 . The subtraction element  22  also has a negative input which is connected to a connecting line  68 . The subtraction element  22  is designed to subtract a signal received at the negative input from a signal received at the positive input and to generate a subtraction result and output the latter on the output side. 
         [0032]    The adding element  24  is connected, on the output side, to a flip-flop  26  via a connecting line  56 . The flip-flop  26  is connected, on the input side, to a clock generator  28  via a connecting line  57 . The flip-flop  26  is connected, on the output side, to a positive input of the adding element  24  via a connecting node  58  and a connecting line  60 . The connecting line  60  forms a feedback loop. The flip-flop  26  thus forms an integrator together with the adding element  24 . The flip-flop  26  is connected, on the output side, to a comparator  30  via the connecting node  58  and a connecting line  59 . The comparator  30  is designed to evaluate a most significant bit (MSB) of a signal received on the input side and to generate an output signal representing the most significant bit (MSB). 
         [0033]    The comparator  30  is connected, on the output side, to a flip-flop  32  which is in the form of a 1-bit memory in this embodiment. The flip-flop  32  is connected, on the input side, to a clock generator  34  via a connecting line  62 . The clock generator  34  and the clock generator  28  are each formed by an oscillating crystal, for example. The flip-flop  32  and the comparator  30  together form a noise generator. The noise generator is used to superimpose noise on the signal generated by the integrator. The flip-flop  32  is connected, on the output side, to a connecting node  64  and to a gate driver  20  via a connecting line  63 . The connecting node  64  is connected to a digital/digital converter  38  via a connecting line  71 . The digital/digital converter  38  is connected, on the output side, to the negative input of the subtraction element  22  via a connecting line  68 . The digital/digital converter  38  is connected, on the input side, to an analog/digital converter  36  via a connecting line  69 . The subtraction element  22 , the adding element  24 , the flip-flop  26 , the comparator  30 , the flip-flop  32 , the clock generators  28  and  34  and the digital/digital converter  38  together form a delta sigma converter  4 . The flip-flop  32  of the delta sigma converter  4  generates a bit stream at the connecting node  64 . The bit stream is transmitted to the digital/digital converter  38  via the connecting line  71 . If a bit representing a logic “one” is received on the input side via the connecting line  71 , the digital/digital converter  38  is designed to convert a signal, which is received on the input side via the connecting line  69 , with quantization of one or more bits, in particular, and to generate an output signal which represents the signal received on the input side via the connecting line  69 . The gate driver  20  is connected, on the input side, to the output of the flip-flop  32  via the connecting node  64  and the connecting line  63 . The gate driver  20  is connected, on the output side, to a gate connection of a first semiconductor switch in the form of a transistor  19  in a transistor half bridge and a further output of the gate driver is connected to a gate connection of a second semiconductor switch in the form of a transistor  17  in the transistor half bridge. If a signal representing a logic “one” is received on the input side, the gate driver  20  is designed to drive the transistor  19  and, if a signal representing a logic “zero” is received the on the input side, the gate driver  20  is designed to drive the transistor  17 . The transistors  17  and  19  in the transistor half bridge are each in the form of metal oxide semiconductor field effect transistors (MOS-FET), metal insulator semiconductor field effect transistors (MIS-FET) or the like, for example. 
         [0034]    A source connection of the transistor  17  is connected to a ground connection  50  and a drain connection of the transistor  17  is connected to a connecting node  70 . A source connection of the transistor  19  is connected to the connecting node  70  and a drain connection of the transistor  19  is connected to a connecting node  65 . The connecting node  65  is connected to the analog/digital converter  36  via a connecting line  66 . The connecting node  65  is also connected to a connection  40  for a voltage supply. The analog/digital converter  36  thus receives the voltage supply potential via the connecting line  66  and the connecting node  65 . The output signal from the digital/digital converter  38  thus represents the supply voltage of the connection  40 , which voltage is modulated by the bit stream at the connecting node  64 . 
         [0035]    The connecting node  70  is connected to the control output  9 . The control output  9  thus receives—depending on which of the transistors  17  or  19  is driven—either the ground potential of the ground connection  50  or the potential of the connection  40 . The control output  9  is connected to a first connection of the field coil  11  via a connecting line  53 . 
         [0036]    The motor  3  also has a rotor control unit  42 . The rotor control unit  42  is connected, on the input side, to the control input  7 . The control input  7  has connections for the field coils. The rotor control unit  42  is connected to the first connection of the field coil  11  via the control input  7  and a connecting line  53 . The rotor control unit  42  is also connected, on the input side, to a first connection of the field coil  13  via the control input  7  and a connecting line  51  and is connected, on the input side, to a first connection of the field coil  15  via the control input  7  and a connecting line  52 . The second connections of the field coils  11 ,  13  and  15  are each connected to one another and thus form a star connection  75  of a star circuit formed by the field coils  11 ,  13  and  15 . The rotor control unit  42  is also connected, on the input side, to the star connection  75  via the control input  7 . The rotor control unit  42  is connected, on the output side, to the pulse generator  44  via a connecting line  46 , is connected, on the output side, to the pulse generator  45  via a connecting line  49  and is connected, on the output side, to the control input  7  of the control device  1  via a connecting line  54 . The rotor control unit  42  is designed to generate the rotor control signal, in particular in the form of an analog signal, on the basis of a rotor position signal received on the input side—an induced voltage generated by a field coil in this exemplary embodiment—and to output said rotor control signal on the output side. For example, the rotor control unit  42  may transmit the rotor control signal to the pulse generator  44 ,  45  or to the pulse generator  10 , on the basis of a signal amplitude and/or phase angle of an induction-generated voltage signal profile of the rotor position signal received at the input  7 , in order to thus generate a rotating magnetic field using the rotor control signal and the field coils and in order to thus cause the rotor  5  to rotate about the shaft  41 . The rotor control signals on the connecting lines  54 ,  46  and  49  are thus in a phase relationship which is produced by the rotor control unit and determines an angular velocity of the rotating magnetic field. Unlike in this exemplary embodiment, the rotor control unit  42  may be connected to Hall sensors, for example, the motor  3  then having a Hall sensor for each field coil in this exemplary embodiment, which Hall sensor is designed to detect a change in a magnetic field and to generate a Hall voltage corresponding to the change. 
         [0037]    For example, the rotor control unit  42  can generate a control pulse using the pulse generator  44  and can transmit said control pulse to the field coil  13  via the connecting line  47 . The rotor  5  can thus be caused to rotate in the clockwise direction, for example. The rotor control unit  42  can then generate a rotor control signal on the basis of an induced voltage signal which is received by the field coil  11  and/or by the field coil  15  and can transmit said rotor control signal to the input  8  of the pulse generator  10  via the connecting line  54 . The delta sigma converter  4  can then convert the rotor control signal received at the input  8  into a bit stream. The delta sigma converter  4  is provided with feedback using a voltage feedback means formed by the digital/digital converter  38  and is designed to generate an output signal which forms the bit stream and can compensate for a supply voltage fluctuation received on the input side via the connecting lines  69  and  66 . 
         [0038]    The adding element  24  forms, together with the flip-flop  26 , an integrator which is designed to add the signal received via the connecting line  55  and to transmit said signal to the comparator  30  via the connecting line  59 . The comparator  30  is designed to generate an output signal if a signal received on the input side exceeds or undershoots a predetermined threshold value. In this exemplary embodiment, the comparator  30  is in the form of a digital threshold value switch. The comparator  30  can transmit the output signal generated using the threshold value method, via the connecting line  61 , to the flip-flop  32  which forms a 1-bit memory in this exemplary embodiment. A bit stream whose bit repetition frequency is determined by the clock generator  34  is thus applied to the connecting node  64 . The bit stream at the connecting node  64  forms the transistor control signal already mentioned. The bit stream at the output of the flip-flop  32 , which is generated in this manner, has a larger frequency range than the rotor control signal received at the input  8  and is transmitted, on the output side, to the gate driver  20  via the connecting line  64 . The rotor control unit  42  is connected to the gate driver  20  via a connecting line  73 . In order to generate the rotating magnetic field, the rotor control unit  42  is designed to generate a disconnection signal which can be used to disconnect the gate driver, with the result that no gate is driven in the disconnected state. 
         [0039]    The delta sigma converter  4  may also have an IIR filter, for example. The IIR filter is then arranged instead of the subtraction element  22  and the integrator formed by the adding element  24  and the flip-flop  26 . Feedback for the IIR filter is then effected using the voltage feedback means formed by the connecting line  68  and the digital/digital converter  38 . 
         [0040]      FIG. 2  shows an exemplary embodiment of a control device  100 . The control device  100  has an input  8  for a rotor control signal, a control output  9  and a connection  40  for a supply voltage. The control device  100  may be part of the motor  3  illustrated in  FIG. 1 . Instead of the control device  1 , the control device  100  can thus be connected, on the input side, to the connecting line  54  and can be connected, on the output side, to the connecting line  53  and to the supply voltage via the connection  40 . The control device  100  has a delta sigma converter having analog components. The delta sigma converter has a subtraction element  72 , a positive input of which is connected, on the input side, to the input  8 . The subtraction element  72  is connected, on the output side, to an integrator  74  via a connecting line  93 . On the output side, the integrator  74  is connected, via a connecting line  94 , to a comparator  76  which is connected, on the output side, to a flip-flop  78  via a connecting line  96 . The flip-flop  78  is connected, on the input side, to a clock generator  82  via a connecting line  97 . On the output side, the flip-flop  78  is connected to a gate driver  80  via a connecting line  98 . The gate driver  80  is connected, on the output side, to a gate connection of a first transistor  84  and is connected, on the output side, to a gate connection of a second transistor  86 . The transistors  84  and  86  may each be in the form of a metal oxide semiconductor field effect transistor (MOS-FET) or a metal insulator semiconductor field effect transistor (MIS-FET) and together form a transistor half bridge. A source connection of the transistor  86  is connected to the ground potential  50  and a drain connection of the transistor  86  is connected to a source connection of the transistor  84  via a connecting node  88 . A drain connection of the transistor  84  is connected to the connection  40  for a supply voltage. The connecting node  88  forms an output of the transistor half bridge and is connected to the control output  9 . 
         [0041]    The control device  100  also has a voltage feedback means for providing feedback for the delta sigma converter. The delta sigma converter is formed by the subtraction element  72 , the integrator  74 , the comparator  76  and the flip-flop  78 . The voltage feedback means has a voltage divider which is formed by the resistors  90  and  92 . A first connection of the resistor  90  is connected to the control output  9  and a second connection of the resistor  90  is connected to a dividing connection  99 . A second connection of the resistor  92  is connected to the dividing connection  99  and a first connection of the resistor  92  is connected to the ground connection  50 . The dividing connection  99  is connected to a negative input of the subtraction element  72  via a connecting line  91 . The potential applied to the control output  9  is thus divided and is fed back to the subtraction element  72  in order to provide feedback for the delta sigma converter. A supply voltage fluctuation is at least partially reduced or completely eliminated in this manner during operation of the control device  100 . 
         [0042]      FIG. 3  shows an exemplary embodiment of signals which have been generated by the control device  1  which is described in  FIG. 1  and to which reference is also made below. 
         [0043]    A graph  110  is illustrated. The graph  110  has an abscissa  112  and an ordinate  114 . In the graph  110 , a curve  111  shows a temporal profile of a supply voltage which is applied to the connection  40 . The abscissa  112  represents a time axis. The times plotted there are indicated in 10 −4  seconds. The curve  111  represents a temporal voltage profile, a voltage of the voltage profile being a constant 12 volts. The graph  110  also shows a curve  116 . The curve  116  shows an exemplary signal profile at the output of the subtraction element  22 , which profile has delta pulses which are successive periodically and in intervals of time. The graph  110  also shows a signal profile  117  which has sawtooth ramps which are successive periodically and in intervals of time. The signal profile  117  occurs, for example, as a response signal to the delta pulses of the signal  116  at the output of the flip-flop  26  and thus also at the connecting node  58 . The comparator  30  thus receives the signal  117  on the input side. The signal  116  has a negative DC voltage component between the delta pulses. This gives rise to a signal profile of the signal  117  that falls in a stepped manner in the event of integration by the adding element  24  together with each clocked output of the flip-flop  26 . In this case, each height of the steps corresponds to the negative DC voltage component of the signal  116  between the delta pulses. 
         [0044]    The graph  110  also shows a digital bit stream. The digital bit stream forms the transistor control signal at the connecting node  64  and is used to drive the transistor half bridge via the gate driver  20 . The digital bit stream comprises control pulses  118 ,  119  and  120 . The control pulses  118 ,  119  and  120  each have a control pulse duration  126 . In this exemplary embodiment, a pulse pause  121  having a pulse pause duration  125  precedes the control pulse  118 . A pulse pause  123  precedes the control pulse  119  and a pulse pause  124  precedes the control pulse  120 . 
         [0045]    The graph  110  also shows a signal profile  122 . The signal profile  122  represents an output signal from the control device  1  at the control output  9  with an inductive load of the field coils of the motor  3 . The output signal which has an original signal profile corresponding to the bit stream is subjected to low-pass filtering by the field coils as an inductive load and thus gains the signal profile  122  as a result of low-pass filtering. 
         [0046]      FIG. 4  shows an exemplary embodiment of a method for generating a load current for generating a torque using a rotor of an electronically commutated motor. In the method, a control signal for moving the rotor is generated in a first step on the basis of a rotor position signal representing a rotor position of the rotor. The control signal is generated using delta sigma conversion and has control pulses and pulse pauses. In another method step  104 , a supply voltage is fed back, via a voltage feedback means, to an input of the delta sigma converter and is subtracted there from the signal received on the input side by means of subtraction. In another method step  106 , the rotor of the electronically commutated motor is moved using the load current and a torque is thus generated. 
         [0047]    An exemplary sampling frequency of the delta sigma converter of the control device is between 10 times and 100 times the rotor rotational speed. The delta sigma converter thus operates with 10-fold to 100-fold oversampling. An exemplary pulse repetition frequency for driving the transistor half bridge is between 2 kilohertz and 1 megahertz, preferably 5 megahertz, particularly preferably 10 megahertz.