Electric machine
阅读说明:本技术 电机 (Electric machine ) 是由 J.库尔菲斯 U.福尔默 于 2018-06-14 设计创作,主要内容包括:本发明涉及一种电机、尤其是电动马达和/或发电机。所述电机具有定子和尤其是永磁地或者为了通电而构成的转子。所述电机具有至少两个子电机。所述子电机分别具有相同的相数。按照本发明,所述电机针对每个子电机具有功率输出级。所述电机也具有至少一个与所述功率输出级相连接的控制单元。所述控制单元构造用于产生用于对所述功率输出级进行操控的脉宽调制的信号。所述控制单元也构造用于如此产生用于所述子电机的PWM信号,使得用于一个子电机的PWM脉冲的分别表示切换时刻的下降边沿或者上升边沿和用于所述子电机中的另一个子电机的PWM脉冲的脉冲中心彼此在时间上错开。(The invention relates to an electric machine, in particular an electric motor and/or generator. The electric machine has a stator and a rotor, which is constructed, in particular, permanently or for the purpose of current supply. The motor has at least two sub-motors. The sub-motors have the same number of phases, respectively. According to the invention, the electric machine has a power output stage for each partial electric machine. The electric machine also has at least one control unit connected to the power output stage. The control unit is designed to generate a pulse-width-modulated signal for controlling the power output stage. The control unit is also designed to generate the PWM signals for the partial motors in such a way that the falling or rising edge of the PWM pulse for one partial motor, which respectively represents the switching time, and the pulse center of the PWM pulse for the other partial motor are offset in time from one another.)
1. An electric machine (1) having a stator (2) and a rotor (11), wherein the electric machine has at least two partial electric machines (3, 4) each having the same number of phases,
it is characterized in that the preparation method is characterized in that,
the electric machine (1) has a power output stage (13, 14) for each sub-electric machine (3, 4), and the electric machine (1) has at least one control unit (17) which is connected to the power output stage (13, 14) and which is designed to generate PWM signals (33, 34) for controlling the power output stage (13, 14), and the control unit (17) is designed to generate the PWM signals (33, 34) for the sub-electric machines (3, 4) in such a way that a falling edge or a rising edge (35), respectively representing a switching time, of a PWM pulse (61) for one sub-electric machine (3) and a pulse center (36) of a PWM pulse (62) for the other sub-electric machine (4) of the sub-electric machines (3, 4) are offset in time from one another.
2. The electric machine (1) according to claim 1,
it is characterized in that the preparation method is characterized in that,
the electric machine (1) has at least one current sensor (15, 16) connected to the control unit (17) and designed to detect a phase current of at least one or all phases of the partial electric machines (3, 4), wherein the control unit (17) is designed to detect a phase current of at least one phase of the partial electric machines (3, 4) during a pulse center (36) of a PWM pulse (62), wherein the switching times of the PWM pulse (61) are offset in time from one another at the pulse center (36) and therefore at the detection time (36) of the current (40).
3. The electric machine (1) according to any of claims 1 or 2,
it is characterized in that the preparation method is characterized in that,
the control unit (17) is designed to: the duty cycle between the PWM pulse duration (65) and the pulse interval duration (66) of the PWM cycle (64) is varied, in particular uniformly, for all phases of the submotors (3, 4), and a time offset between the pulse edge (35, 35') of the submotor (3) and the pulse center (36) of the PWM pulse (62) for at least one further submotor (4) is thus produced.
4. The electric machine (1) according to any of the preceding claims,
it is characterized in that the preparation method is characterized in that,
the control unit (17) is designed to vary the pulse durations (65, 65') of the high-side and low-side pulses alternately with one another.
5. The electric machine (1) according to any of the preceding claims,
it is characterized in that the preparation method is characterized in that,
the control unit (17) is designed to change the duty cycle for the phase to an upper limit (77) of the lower modulation range (70), in particular.
6. The electric machine (1) according to any of the preceding claims,
it is characterized in that the preparation method is characterized in that,
the control unit (17) is designed to: a current detection interval (40) is generated and the current is detected during the current detection interval (40) and the duty cycle (65, 66) is changed, in particular expanded or reduced, in such a way that, in particular, a rising or falling edge (35) coincides with a start (38) or end time (39) of the current detection interval (40) or lies outside the current detection interval.
7. The electric machine (1) according to any of the preceding claims,
it is characterized in that the preparation method is characterized in that,
the control unit (17) has a pulse width modulator (18) which is designed to vary the duty cycle (65, 66) for at least one or more PWM periods (64).
8. Method for controlling an electric machine (1) having at least two partial electric machines (3, 4), wherein the sub-motors each have the same number of stator coils (5, 6, 7, 8, 9, 10), wherein pulse-width-modulated pulse patterns (33, 34) are generated for controlling the stator coils (5, 6, 7, 8, 9, 10), wherein the current flowing through at least one of the stator coils (5, 6, 7, 8, 9, 10) is detected in a time range (40) of a pulse center (36), and wherein the duty cycle (65, 66) of the PWM cycle (64) for at least one other sub-motor (3) is changed, in particular lengthened or shortened, the pulse start and/or pulse end of the PWM pulse (61) is/are offset in time with respect to the current detection, in particular with respect to the pulse center (36).
9. The method of claim 8, wherein the first and second light sources are selected from the group consisting of,
wherein the current is detected within a current detection interval (40) including the instant of the pulse center (36).
10. Method according to any of the preceding claims, wherein the duty cycle (65, 66) of the other sub-motors (4) is half of the full modulation of the motor.
Technical Field
The invention relates to an electric machine, in particular an electric motor and/or generator. The electric machine has a stator and a rotor, which is constructed, in particular, permanently or for the purpose of current supply. The motor has at least two sub-motors. The sub-motors have the same number of phases, respectively. The partial motors preferably each have a part of the stator coils of the stator and are each designed to generate a rotating magnetic field for the rotary movement of the rotor independently of one another. The electric machine, in particular the stator, preferably has at least one, at least two, at least three or only one stator coil for each phase of the partial electric machine.
Background
DE 102005043576 a1 discloses a method for operating an electric machine having at least two electrically separate stator windings, wherein a first stator winding is fed by a first subinverter and a second stator winding is fed by a second subinverter. The subinverters are controlled by means of staggered beat signals.
Disclosure of Invention
According to the invention, the electric machine has a power output stage for each partial electric machine. The electric machine also has at least one control unit connected to the power output stage. The control unit is designed to generate a pulse-width-modulated signal for controlling the power output stage. The control unit is also designed to generate the PWM signals for the partial motors in such a way that the pulse centers of the PWM pulses for the one partial motor, which respectively represent the switching times, and the PWM pulses for the other of the partial motors are offset in time from one another.
It has thus been recognized that, in the case of rising or falling edges of PWM pulses generated for switching the stator coils of the stator, the current detection of the stator coil current at the time of the pulse center of the PWM pulse can be disturbed in an advantageous manner. The power output stage supplies the stator coil with a switching edge controlled by a PWM pulse, which generates an electromagnetic field that may interfere with the current detection, in particular the current measurement, of the stator coil current of the other stator coil. The disturbance can occur in particular if the pulse patterns generated with respect to the partial motors, which are also referred to as PWM signals before, differ from one another or if the PWM control of the partial motors are carried out offset in time from one another.
Preferably, each partial motor (which partial motor preferably comprises a part of the stator coils of the stator) is designed to generate a magnetic field for a rotational movement of the rotor, in particular for a complete rotation of the rotor. The sub-motors are preferably each electrically connected to and can be supplied by the same intermediate circuit. The control unit is preferably configured to: the submotors are actuated offset from one another (preferably by applying PWM signals to the power output stage). This advantageously relieves the intermediate circuit capacitors connected to the intermediate circuit from being loaded. The phase offset between the operating modes of the partial motors is preferably between 20 and 30% of the PWM period, particularly preferably 25% of the PWM period. Thereby, the intermediate circuit capacitors can supply power to the sub-motors alternately with each other.
In a preferred embodiment, the electric machine has at least one current sensor connected to the control unit. The current sensor is designed to detect the current of at least one or all phases of the partial electric machine. The control unit is designed to detect the phase current of at least one phase of the partial motor during the pulse center of the PWM pulse, the switching times of the PWM pulse being offset in time from one another in the pulse center and therefore in the detection time of the current. The electric machine preferably has at least one current sensor for each submotor. The current sensor can be designed, for example, as a shunt resistor. The current sensor can advantageously be used to detect the phase current of a phase of the partial motor and to generate a current signal representing the phase current. The control unit is preferably connected on the input side to the current sensor and can therefore advantageously receive the current signal as a control variable or control input variable for controlling the power output stage by the control unit.
In a preferred embodiment, the control unit is configured to: the duty cycle between the PWM pulse duration and the pulse interval duration of the PWM period is varied, in particular uniformly, for all phases of the partial motors, and thus a time offset between the pulse edge of the partial motor and the pulse center of the PWM pulse for at least one further partial motor is produced. The voltage offset of the voltage vectors of the partial motors is produced by simultaneously varying the duration of the PWM pulses for all stator coils of the partial motors, but this advantageously has no effect on the potential differences of the phases of the partial motors relative to one another.
In a preferred embodiment, the control unit is configured to: the pulse duration of the high-side pulse generated by the high-side semiconductor switch of the power output stage and the pulse duration of the low-side pulse which can be generated by the low-side semiconductor switch of the same power output stage are changed alternately with one another. The power loss in the power output stage, which is additionally generated by pulse lengthening, can thus be distributed uniformly between the high-side semiconductor switch and the low-side semiconductor switch.
In a preferred embodiment, the control unit is designed to vary the duty cycle for the phase to an upper limit, in particular of the lower modulation range. A negative voltage value of the formed voltage vector can thus advantageously be avoided when a predetermined duration of time is subtracted from the PWM pulse duration of the PWM pulse.
In a preferred embodiment, the control unit is designed to generate a current detection interval and to detect the current during the current detection interval. The control unit is preferably further designed to vary, in particular to increase or decrease, the duty cycle in such a way that, in particular, a rising or falling edge coincides with the beginning or end time of the current detection interval or lies outside the current detection interval. The operating voltage generated by the control unit by means of PWM modulation for operating the power output stage can therefore advantageously reach the limit of the current detection interval, so that the control of the operating voltage to be applied to the phases of the power output stage, in particular the power output stage, can advantageously take place within a voltage interval that reaches a voltage interval determined by the time window of the current detection interval, which is not permissible in particular. The operating voltage generated by the control unit by means of PWM modulation for operating the power output stage corresponds here to the modulation of the electric machine determined by the duty cycle of the PWM modulation.
In a preferred embodiment, the control unit has a pulse width modulator which is designed to vary the duty cycle for at least one or more PWM periods. The control unit can thus advantageously adjust the voltage to be applied to the stator coil by means of the pulse width modulator by means of a change in the duty cycle.
The invention also relates to a method for controlling an electric machine having at least two partial electric machines. The sub-motors have the same number of stator coils, respectively. In the method, a pulse-width-modulated pulse pattern is generated for actuating the stator coils, wherein the current flowing through at least one of the stator coils is detected in the time range of the pulse center. In the method, the duty cycle of the pulse period for at least one other partial motor is changed, in particular lengthened or shortened, in such a way that the pulse start and/or pulse end of the PWM pulse is separated in time from the current detection, in particular from the pulse center.
In a preferred variant of the method, the current is detected within a current detection interval that includes the instant of the pulse center. The current detection in the region of the pulse center can advantageously be controlled by the PWM cycle of the preferably centrally generated PWM pulse, which is generated by the pulse width modulator. For example, the current detection can take place in every PWM period, every second, every third or every fourth PWM period or only in PWM periods following one another indirectly, between which a predetermined number of PWM periods are comprised, so that no current detection takes place in the included PWM periods.
Preferably, the duty cycle in the other sub-motors is half and thus 50% of the full modulation, the PWM pulses for the other sub-motors being lengthened or shortened. For this modulation value, the pulse center of the control pulse for the further partial motor coincides with the pulse edge of the control pulse for the partial motor. When the current detection is performed on the current of another sub-motor at the time or within the time range of the pulse center, the current detection may be disturbed by the edges of the control pulses of the other sub-motor. For this purpose, the phase offset of the PWM control between the two partial motors is, for example, 25% of the PWM period.
Further preferably, the range to be avoided of the duty cycle of the sub-motors is between 50% and 60% of the full modulation and/or between zero and 10% of the full modulation. This advantageously allows for an undisturbed current detection at the partial motor. For other phase offsets of the PWM control between the partial motors, other modulation ranges to be avoided result.
Drawings
The invention will now be described below with the aid of figures and other embodiments. Further advantageous embodiments result from the features described in the dependent claims and the figures.
Fig. 1 shows an exemplary embodiment for an electric machine which is designed to vary the pulse duration of a PWM pulse as a function of a current detection of the drive current of a further partial electric machine in such a way that the current detection is not disturbed by the switching edges of the PWM pulse;
fig. 2 shows a diagram in which control pulses for the actuation of two mutually different sub-motors are shown;
fig. 3 shows a diagram in which the offset displacement of the voltage profile at the stator coil caused by the lengthening of the pulse duration is shown;
fig. 4 shows the voltage profiles at the three stator coils of the partial motor, wherein the modulation range, in particular the middle, is skipped in the profile change;
fig. 5 shows the voltage profile at the three stator coils of the submotor, wherein two modulation regions are skipped in the profile change.
Detailed Description
Fig. 1 schematically shows an embodiment for an
The
The control unit 17 is in this exemplary embodiment designed to actuate the
The control unit 17 has a
The
The control unit 17 is designed to detect the current signals generated by the
The control unit 17, for this purpose the
Fig. 2 shows a diagram in which two mutually different pulse pattern signals for two mutually different stator coils of mutually different sub-motors are schematically shown. The graph includes a
The pulse pattern signal represented by
The
The adding
Fig. 3 schematically shows a diagram with an abscissa 42 representing a time curve and an ordinate 43 representing a signal amplitude. Fig. 3 shows an exemplary voltage profile on the stator coil, which is averaged in each case over a PWM period, in particular over a short time, and which is generated by the pulse-width-modulated signal represented by the
The extended control pulse 35' shown in fig. 2 now causes an offset displacement 46 of the offset of the voltage curve represented by curve 44. Fig. 3 also shows a curve 44' which represents the curve 44 shifted out of the
Fig. 4 schematically shows a diagram in which a curve 50, a curve 51 and a curve 52 are shown. The graph has a time axis 48 and an amplitude axis 49. The curves 50, 51 and 52 each represent a voltage curve at mutually different stator coils of the partial motor, for example the voltage curves at the three
In this case, the curve 50 corresponds, for example, to the voltage curve at the
Also shown is a
The voltage profile on the
Fig. 5 schematically shows a diagram in which curves 73, 74 and 75 representing voltage curves, respectively, are shown. The graph has a
The
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