DE102008052144B4 - Synchronous machine and method for operating a synchronous machine - Google Patents

Abstract

Method for operating a drive system with a synchronous machine which is powered by an electronic circuit, the electronic circuit comprising a commutation unit (3) which is supplied from a power actuator (2) which is supplied from a unipolar voltage source, the commutation unit ( 3) is operated in a block-commutated manner, i.e. in such a way that the frequency of the block-shaped output voltage of the commutation unit (3) corresponds to the electrical stator frequency, and in such a way that the effective value of the output voltage is directly proportional to the intermediate circuit voltage, i.e. the voltage supplying the commutation unit (3), wherein the effective value of a motor phase current is recorded or determined and the phase of the first harmonic of the motor current time curve is determined relative to the electrical rotor angular position and regulated to zero, whereby operation is regulated towards optimal motor loss operation by using the switching times for the semiconductor switches of the commutation unit as the manipulated variable of the associated controller (3) can be used, with the switching times being shifted relative to the electrical motor angular position depending on the motor current.

Description

The invention relates to a synchronous machine and a method for operating a synchronous machine.

Synchronous motors are known as synchronous machines that carry permanent magnets on their rotor, in particular radially magnetized permanent magnets alternately oriented in the circumferential direction. The stator is intended to generate a rotating field.

From the EP 1 598 930 A2 The closest prior art is a motor drive unit.

From the EP 1 300 936 A2 a drive unit is known.

From the DE 10 2004 002 414 A1 a motor control is known.

From the DE 10 127 670 A1 a control of a three-phase brushless electric motor is known.

From the DE 10 2004 030 326 A1 an electronically commutated electric motor is known.

The invention is therefore based on the object of enabling improved control properties in a synchronous machine.

According to the invention, the object is achieved in the synchronous machine according to the features specified in claim 6 and in the method according to the features specified in claim 1.

Important features of the invention in the drive system are that it includes an electric synchronous machine and an electronic circuit that feeds it,
wherein the electronic circuit comprises a commutation unit powered by a power actuator powered by a unipolar voltage source.

The advantage here is that a high speed and a very dynamic change in torque are possible. The power can be regulated directly using the power actuator, with the actual torque value following the setpoint specifications very quickly. Furthermore, the motor current and motor voltage are adjusted and no measurement of these variables is necessary. The exception to this may be if the angle sensor is not used. In this case, it is necessary to record the motor current and motor voltage. In addition, control is robust and simple.

It is also advantageous that the power of the motor or, if the speed is known, the torque can be adjusted by the power actuator - but not by the commutation unit, i.e. the actual converter. This means that the power control is decoupled from the motor control and can be carried out quickly and directly in a particularly simple and robust manner.

The motor control is robust and simple as a simple commutation circuit is used. The motor inverter has a low switching frequency because this switching frequency corresponds to the electrical stator frequency, and thus low switching losses of the power semiconductor switches occur.

The switching frequency of the power actuator is independent of the pole change frequency of the machine.

It is also advantageous that very high speeds of up to 20,000 or even 100,000 revolutions per minute are possible, especially with a limited supply voltage.

In an advantageous embodiment, the power actuator is designed as a four-pole, at the input of which a unipolar voltage source, in particular battery voltage, and from the output of which the commutation unit is supplied,
wherein the input current of the four-pole is supplied via an inductance to the connection node of two series-connected controllable semiconductor switches, in particular upper and lower semiconductor switches connected in series, in particular wherein the semiconductor switches are designed and / or are designed to be controllable in a pulse-width modulated manner by signal electronics. The advantage here is that a higher voltage can be available on the four-pole output side than at the input.

In an advantageous embodiment, the control signals, in particular pulse width modulated control signals, are generated for the semiconductor switches in such a way that the input current detected by means of current detection means is regulated to a desired value, in particular the control unit being supplied with the input voltage and output voltage of the power actuator and/or the four-pole detected by voltage detection means become. The advantage here is that a simple controller can be used.

In an advantageous embodiment, the setpoint for input current is provided as a manipulated variable of a controller, which determines an actual value for instantaneous power from the detected input current value and from the detected input voltage value and regulates this to a predeterminable setpoint for power, in particular where the control size is a linear function or a linear functional of the target-actual deviation of the performance. The advantage is that this control has a similar effect to a simple and direct torque controller.

In an advantageous embodiment, the controller and/or the control unit is designed as a linear controller. The advantage here is that a simple and cost-effective structure is sufficient.

In an advantageous embodiment, a sensor is provided for detecting the angular position of the rotor. The advantage here is that the control dynamics and control accuracy can be improved.

In an advantageous embodiment, the rotor of the synchronous machine and the driven and/or driving rotatably mounted parts connected to it have such a high moment of inertia that the torque can be changed faster than the speed, in particular at least at a rate of change ten times faster. The advantage here is that the torque is influenced approximately directly and immediately and the torque therefore follows the specified target value quickly and precisely.

In an advantageous embodiment, a sensor for detecting the angular position of the rotor and/or a sensor for detecting the rotor temperature is provided on the rotor. The advantage here is that control can be implemented in an improved manner and, particularly when the rotor temperature is taken into account, even changes in route size values can be taken into account. This means that control fluctuations can be further reduced and the control quality can be further improved.

In an advantageous embodiment, the rotor of the synchronous machine and the driven and/or driving rotatably mounted parts connected to it have such a high moment of inertia that the torque can be changed faster than the speed, in particular at least at a rate of change ten times faster. The advantage here is that the torque can be changed very quickly and thus a torque generated, for example, by the synchronous machine can be added to the output torque of an internal combustion engine, with the speed of the internal combustion engine having a high inertia and thus appearing constant on the time scale of the torque change. Instead of an internal combustion engine, another device with a large moment of inertia, such as a flywheel, can also be used.

Important features of the method are that the method is intended to operate a drive system with a synchronous machine that is fed by an electronic circuit,
wherein the electronic circuit comprises a commutation unit which is powered by a power actuator which is powered by a unipolar voltage source,
wherein the commutation unit is operated in a block-commutated manner, in particular in such a way that the frequency of the block-shaped output voltage of the commutation unit corresponds to the electrical stator frequency, and/or in such a way that the effective value of the output voltage is directly proportional to the intermediate circuit voltage, i.e. the voltage supplying the commutation unit.

The advantage here is that a direct and rapid influence on the torque-generating variable can be carried out and thus a high level of dynamic control can be achieved.

In an advantageous embodiment, the rate of change of the speed is lower than the rate of change of the manipulated variable, in particular where the nominal values are related to the nominal variable values of the machine. The advantage here is that the torque can be changed very quickly and can therefore be passed on at a constant speed, for example adding it to a torque generated by another machine. For this purpose, the rotor shaft can be mechanically coupled or directly connected to the output shaft of an internal combustion engine.

• - zur erfassten Winkellage des Rotors oder
• - zur aus erfassten Motorstrom- und Motorspannungsmesswerten bestimmten Winkellage des Rotors

ausgeführt, insbesondere also werden die Schaltsignale für die Halbbrücken der Kommutierungseinheit synchron zur Winkellage bestimmt. Von Vorteil ist dabei, dass eine einfache Regelung bei geringem Rechenaufwand realisierbar ist und somit eine hohe Drehzahl ermöglicht istIn an advantageous embodiment, the commutation is synchronous

• - for the detected angular position of the rotor or
• - the angular position of the rotor determined from the measured motor current and motor voltage values

executed, in particular the switching signals for the half bridges of the commutation unit are determined synchronously to the angular position. The advantage here is that simple control can be implemented with little computational effort and thus a high speed is possible

In an advantageous embodiment, the effective value of the motor phase current is recorded or determined
and/or the switching times for the semiconductor switches of the commutation unit are used as a manipulated variable for a control, in particular the switching times are shifted relative to the electrical motor angular position as a function of the motor current. The advantage here is that no complex pulse width modulation can be used, but rather a simple procedure

In an advantageous embodiment, the effective value of the motor phase current is recorded or determined.
and/or the phase of the first harmonic of the motor current time curve is determined relative to the electrical rotor angular position,
wherein the operation is controlled for optimal motor loss by using the switching times for the semiconductor switches of the commutation unit as the manipulated variable of the associated controller, in particular the switching times are shifted relative to the electrical motor angular position depending on the motor current. The advantage here is that the loss lines have a short shelf life.

In an advantageous embodiment, the rotor angular position is determined from detected motor current values and motor voltage values, in particular where no angle sensor connected to the rotor shaft is used. The advantage here is that no additional sensor is necessary and the design can therefore be implemented simply and cost-effectively.

In an advantageous embodiment, the speed of the rotor is essentially constant. In particular, the rate of change of the speed is lower than the rate of change of the manipulated variable, in particular where the nominal values are related to the nominal variable values of the machine. The advantage here is that a driven device with a high moment of inertia can be connected and the torque can therefore be controlled directly without significantly changing the speed.

Further advantages result from the subclaims.

• In der 1 ist eine erfindungsgemäße Vorrichtung schematisch skizziert.

The invention will now be explained in more detail using illustrations:

• In the 1 a device according to the invention is schematically sketched.

From an energy storage device 1, which is designed, for example, as a battery, with a voltage U _e or another energy source supplying a unipolar voltage, a power actuator 2 is supplied to generate an output voltage U _a , from which a commutation unit 3 is supplied with an intermediate circuit capacitor, which has a Electric motor 4, i.e. electric machine, feeds. The output voltage U _a is preferably greater than the voltage U _e .

A sensor 5 for detecting the rotor position angle is arranged on this electric motor, preferably a synchronous motor, the sensor signals of which are fed to a sensor signal evaluation 6. The sensor information is fed to signal electronics 7 with commutation logic, which also controls the control signals of the switches of the commutation unit 3. The commutation unit 3 is composed of three half-bridges arranged in parallel, each half-bridge being composed of a series connection of an upper and a lower semiconductor switch.

Block commutation is preferably carried out here, so that very high speeds can be achieved, in particular up to 100,000 revolutions per minute and more.

The input current i _e of the power actuator 2 is detected and supplied to an inductor L _ST , which is at the node of a series connection of the controllable switches (T _o , Tu), which are preferably designed as semiconductor switches.

The output voltage of the power actuator is smoothed by the intermediate circuit capacitor C _d and fed to the output stage of the commutation unit 3, which comprises the three half-bridges, each of which has a series connection of power switches. The stator windings of the synchronous motor are supplied from the output stage 1. A diode is also connected in parallel to each circuit breaker. The output stage is able to transport energy from the capacitor to the stator windings and from the stator windings to the capacitor.

The switches of the commutation unit 3 are clocked depending, in particular synchronously, on the detected angular position. Block commutation is preferably carried out so that high motor speeds of up to 100,000 revolutions per minute can be carried out with little loss.

The detected actual values of the input voltage U _e and the input current i _e as well as the detected output voltage U _a , which corresponds to the intermediate circuit voltage of the commutation unit, are supplied to the current controller 8 and regulated to the setpoint of the input current i _{e, setpoint} , which is specified by the higher-level power controller 9 becomes. The control signals for the lower and upper switches of the power actuator 2 are used as the manipulated variable. Pulse width modulated control signals are preferably used here, so that the pulse widths T _O and T _U are then used as the manipulated variables.

To generate the setpoint specification i _{e, setpoint} acts as the manipulated variable of the power controller 9, this power controller 9 is supplied with the recorded actual values of the input voltage U _e and the input current i _e , from which the associated power P _e = U _e × i _e is determined and this specific power value regulated as an actual variable by the controller to a specified target value for power.

The stator windings of the electric motor M can be designed as a three-phase winding according to the state of the art. In any case, they are designed in such a way that a rotating field can be generated in the area of the rotor.

According to the invention, it is therefore possible to regulate the motor in such a way that the speed is kept essentially constant and the torque is regulated to a target value by means of the power specification. Keeping the speed constant is achieved by the load to be driven connected to the rotor. This load is, for example, designed with a high moment of inertia and/or can be designed as a shaft driven by an internal combustion engine.

Since the commutation unit, i.e. output stage, is operated with block clocking, the frequency of the block-shaped output voltage on the motor side corresponds to the electrical stator frequency and the associated effective value is directly proportional to the voltage at capacitor C_1.

Since the angular position of the rotor is detected by an angle sensor, the switches are easily switched depending on the respective angle value.

According to the invention, the energy flow is made possible in both directions. In generator operation of the engine, for example in a hoist, the energy storage is filled, while in motor operation, energy is taken from this energy storage.

Because of the block clocking, the frequency of the block-shaped output voltage corresponds to the electrical stator frequency and its effective value is directly proportional to the intermediate circuit voltage U _d . The effective value of the output voltage with a fixed DC link voltage cannot therefore be reduced.

Because of the high moment of inertia on the load side and the therefore essentially constant speed as well as because of the constant excitation that is present by means of the permanent magnets of the synchronous motor arranged on the rotor, the pole wheel voltage is predetermined.

Since the detected rotor angle is taken into account when generating the control signals for the semiconductor switches of the commutation unit, the frequency of the machine terminal voltage is adapted to the speed of the machine.

The power actuator regulates the motor power without directly knowing and/or regulating the phase voltages or phase currents of the electric machine by changing U _d and thus the effective value of the machine terminal voltage.

The power can be regulated, for example, at the input of the actuator and then corresponds to the mechanical motor power plus the power loss in stationary operation and minus the power loss in generator operation.

• Bei der ersten Ausführungsvariante wird im motorischen Betrieb eine feste Phase zwischen angelegter blockförmiger Spannung und Rotorwinkellage vorgegeben. Die Schaltzeitpunkte der Halbleiterschalter der Kommutierungseinheit werden entsprechend vorgesehen. Im generatorischen Betrieb werden die Halbleiterschalter nicht angesteuert, wobei dann die Kommutierungseinheit einen einfachen Gleichrichter darstellt.

The following three alternative versions are advantageous for changing the phase of the machine terminal voltage:

• In the first embodiment variant, a fixed phase is specified between the applied block-shaped voltage and the rotor angular position during motor operation. The switching times of the semiconductor switches of the commutation unit are provided accordingly. In generator operation, the semiconductor switches are not controlled, with the commutation unit then representing a simple rectifier.

In the second embodiment variant, the effective value of the motor phase current is determined or recorded with a sensor. The semiconductor switches of the commutation unit are also controlled in generator operation and the first harmonic of the current can therefore be influenced in relation to the first harmonic of the motor voltage. By shifting the switching times of the semiconductor switches of the commutation unit in relation to the rotor angular position, such control of the phase as a function of the motor current is made possible so that low-loss motor operation is achieved in both generator and motor operation when the machine parameters are known.

In the third embodiment variant, the relative phase position between the first harmonic of one or more motor phase currents and the detected rotor angular position is determined. The phase angle between the rotor position and the magnet wheel voltage is fixed and known. The phase position between the magnet wheel voltage and one or more phase currents can thus be determined as an actual value. By shifting the switching times of the semiconductor switches of the commutation unit in relation to the rotor angular position, the phase of the motor current in relation to the pole wheel voltage can be controlled. In this control, the switching times are used as a manipulated variable. The aim of the control is to regulate the relative phase position mentioned to zero, i.e. to make the phase of the motor current as in-phase as possible with the pole wheel voltage. In this way, the losses can be reduced; the operating point with the lowest engine losses can be achieved, especially in both generator and motor operation regulate. This can even be carried out without knowledge of the machine parameters.

In further exemplary embodiments according to the invention, instead of a three-phase motor 1 a single-phase motor or a polyphase motor is used. The number of half bridges of the commutation unit 3 is selected accordingly.

In further exemplary embodiments according to the invention, the angle sensor is dispensed with, with motor voltages and motor currents being recorded and taken into account by the control system.

Reference symbol list

1

Energy storage or energy source

2

Power actuator

3

Commutation unit with intermediate circuit capacitor

4

Electric motor

5

Sensor for detecting the rotor position angle

6

Sensor signal evaluation

7

Signal electronics with commutation logic

8th

Current regulator

9

Power regulator

Claims (6)

Method for operating a drive system with a synchronous machine, which is powered by an electronic circuit, wherein the electronic circuit comprises a commutation unit (3) which is supplied from a power actuator (2) which is supplied from a unipolar voltage source, wherein the commutation unit (3) is operated in a block-commutated manner, i.e. in such a way that the frequency of the block-shaped output voltage of the commutation unit (3) corresponds to the electrical stator frequency, and in such a way that the effective value of the output voltage is directly proportional to the intermediate circuit voltage, i.e. that which supplies the commutation unit (3). tension, is, wherein the effective value of a motor phase current is detected or determined and the phase of the first harmonic of the motor current time curve is determined relative to the electrical rotor angular position and regulated to zero, wherein the operation is controlled for optimal motor loss by using the switching times for the semiconductor switches of the commutation unit (3) as the manipulated variable of the associated controller, the switching times being shifted relative to the electrical motor angular position depending on the motor current. Procedure according to Claim 1 , characterized in that the commutation is carried out synchronously - to the detected angular position of the rotor or - to the angular position of the rotor determined from detected motor current and motor voltage measured values, in particular the switching signals for the half bridges of the commutation unit (3) are determined synchronously to the angular position. Method according to at least one of the preceding claims, characterized in that the rotor angular position is determined from detected motor current values and motor voltage values, in particular in which no angle sensor connected to the rotor shaft is used. Method according to at least one of the preceding claims, characterized in that the speed of the rotor is essentially constant. Method according to at least one of the preceding claims, characterized in that the rate of change of the speed is lower than the rate of change of the manipulated variable, in particular wherein the nominal values are related to the nominal variable values of the machine. Drive system, comprising a synchronous machine and an electronic circuit feeding it for carrying out a method according to one of Claims 1 until 5 , wherein the electronic circuit comprises a commutation unit (3) which is supplied from a power actuator (2) which is supplied from a unipolar voltage source, the power actuator (2) being designed as a four-pole, at the input of which there is a unipolar voltage source, i.e. battery voltage , and from whose output the commutation unit (3) is supplied, the input current of the four-pole being supplied via an inductor to the connection node of two controllable semiconductor switches connected in series, i.e. upper and lower semiconductor switches connected in series, the semiconductor switches being supplied by signal electronics (7 ) are designed and/or controlled in a pulse width modulated manner, the control signals, i.e. pulse width modulated control signals, being generated for the semiconductor switches in such a way that the input current detected by means of current detection means is regulated to a desired value, the control unit receiving the input voltage detected by voltage detection means Voltage and output voltage of the power actuator (2) and / or the four-pole are supplied, the setpoint for input current being provided as a manipulated variable of a controller, which determines an actual value for instantaneous power from the detected input current value and from the detected input voltage value and sets this to a predeterminable setpoint for Regulates power, the manipulated variable being a linear function or a linear functional of the target/actual deviation of the power, the controller and/or the control unit being designed as a linear controller, with a sensor (5) for detecting the angular position of the rotor is provided, wherein the rotor of the synchronous machine and the driven and / or driving rotatably mounted parts connected to it have such a high moment of inertia that the torque can be changed faster than the speed at least with a rate of change ten times faster.

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