DE102018002188A1 - Method for testing a drive and drive - Google Patents

Abstract

A method of testing a drive and drive, the drive comprising an electric motor powered by an inverter, the electric motor having a rotor rotatably mounted relative to a stator, the stator having stator windings fed from a voltage system provided by the inverter at its AC voltage-side connection is provided, wherein in a first method step by means of the inverter at the AC side terminal of the inverter, a static voltage system for supplying the stator windings are provided and each of the stationary adjusting value of the current flowing through a respective stator winding detected current from the voltage system, In particular, at least one resistance value is determined from the respectively provided voltage and the values, wherein the resistance value is monitored for unacceptably high deviation from a reference value, in particular and at Exceeding the impermissibly high deviation warning information is displayed and / or weiterverleitet.

Description

The invention relates to a method for testing a drive and a drive.

It is well known that a drive comprises a converter-fed electric motor, wherein the converter is designed as a frequency converter and provides a rotary voltage for the motor.

From the DE 11 2014 003 571 T5 is an automated engine adaptation known.

From the EP 2 933 647 A1 is a model-based diagnosis for an induction machine known.

From WO 2009/009 232 A2 a method for determining the stator winding resistance in an AC motor is known.

The invention is therefore the object of developing the safety in the operation of a drive.

According to the invention, the object in the method according to claim 1 and 3 and solved in the drive according to the features indicated in claim 8.

$$\frac{1}{R_{wu}}=\frac{1}{3R{S}_w}-\frac{1}{3R{S}_v}+\frac{1}{3R{S}_u}$$

$$\frac{1}{R_{uv}}=\frac{1}{3R{S}_u}-\frac{1}{3R{S}_w}+\frac{1}{3R{S}_v}$$

wobei dann ein Verhältnis gebildet wird, insbesondere gemäß $$Verh\text{ä}ltnis=\frac{Max\left(R_u,R_v,R_w\right)}{Min\left(R_u,R_v,R_w\right)}$$

wobei das Verhältnis auf unzulässig hohe Abweichung von einem Sollwert, insbesondere ein Wert aus dem Bereich zwischen 1,1 bis 1,5 , insbesondere 1,2 überwacht wird, insbesondere und bei Überschreiten der unzulässig hohen Abweichung eine Warninformation angezeigt und/oder weitergleitet wird.Important features in the method for testing a drive according to claim 1 are that
the drive has an electric motor fed by an inverter,
wherein the electric motor has a rotor rotatably mounted relative to a stator,
the stator having stator windings fed from a voltage system provided by the inverter at its AC side terminal,
in particular, wherein the voltage system is formed of voltages each feeding a respective one of the stator windings,
wherein in a first method step by means of the inverter at the AC-side terminal of the inverter, a first static voltage system (+ u, -u / 2, -u / 2), in particular in a first period constant voltages, are provided for feeding the stator windings and each of the stationary value of the current flowing through a respective stator winding is detected, in particular determined,
wherein at least one first resistance value is determined from the voltage system, in particular from the respectively provided voltage and the values, in particular according to Ohm's law RS_u = u / i_u,
in a second method step by means of the inverter at the AC-side terminal of the inverter, a second static voltage system (-u / 2, + u, -u / 2), in particular in a first period constant voltages, are provided for feeding the stator windings and each of himself detects, in particular determines, stationary value of the current flowing through a respective stator winding.
wherein at least one second resistance value is determined from the second voltage system, in particular from the respectively provided voltage and the values, in particular according to Ohm's law RS_v = u / i_u,
in a third method step by means of the inverter at the AC-side terminal of the inverter, a third static voltage system (-u / 2, -u / 2, + u), in particular in a first period constant voltages are provided for feeding the stator windings and each of themselves detects, in particular determines, stationary value of the current flowing through a respective stator winding.
wherein at least one third resistance value is determined from the third voltage system, in particular from the respectively provided voltage and the values, in particular according to Ohm's law RS_W = u / i_W,
wherein thereafter different resistance values (R_u, R_v, R_W) are determined from the first, second and third resistance values, in particular according to $$\frac{1}{R_{vw}}=\frac{1}{3R{S}_v}-\frac{1}{3R{S}_u}+\frac{1}{3R{S}_w}$$

$$\frac{1}{R_{wu}}=\frac{1}{3R{S}_w}-\frac{1}{3R{S}_v}+\frac{1}{3R{S}_u}$$

$$\frac{1}{R_{uv}}=\frac{1}{3R{S}_u}-\frac{1}{3R{S}_w}+\frac{1}{3R{S}_v}$$

wherein then a ratio is formed, in particular according to $$VerH\text{ä}ltnis=\frac{Max\left(R_u.R_v.R_w\right)}{Min\left(R_u.R_v.R_w\right)}$$

wherein the ratio is monitored for impermissibly high deviation from a desired value, in particular a value from the range between 1.1 to 1.5, in particular 1.2, in particular and when exceeding the impermissibly high deviation warning information is displayed and / or weiterleitleitet.

The advantage here is that the security can be improved in a little expensive way.

Important features of the invention in the method for testing a drive according to claim 3 are that the drive has an electric motor fed by an inverter,
wherein the electric motor has a rotor rotatably mounted relative to a stator,
the stator having stator windings fed from a voltage system provided by the inverter at its AC side terminal,
in particular, wherein the voltage system is formed of voltages each feeding a respective one of the stator windings,
wherein in a first method step by means of the inverter at the AC-side terminal of the inverter, a static voltage system, in particular in a first period constant voltages are provided for feeding the stator windings and each detects the stationary adjusting value of the current flowing through a respective stator winding current, in particular determined , becomes,
wherein at least one resistance value is determined from the voltage system, in particular from the respectively provided voltage and the values, in particular according to Ohm's law,
wherein the resistance value is monitored for inadmissibly high deviation from a reference value, in particular and when the impermissibly high deviation is exceeded, warning information is displayed and / or passed on.

The advantage here is that the drive can be tested in a simple manner without additional resources. In this case, the frequency converter which is present anyway can be used, which provides the motor with a voltage and detects and / or determines the current caused thereby. Because the underlying inventive idea is that a static, so temporally immutable motor voltage space pointer is provided. Thus, the inverter of the inverter at its Weichselspannungsseitigen connection provides three static potentials, which are referred to the mass or a zero potential as three voltages. Since these potentials are static, ie temporally immutable in a first period of time, a motor current space vector appears after a transient, whereby preferably the rotor is demagnetized and / or does not rotate relative to the stator. Particularly advantageous so the brake has fallen.

In an advantageous embodiment, in at least one subsequent method step in a different time period, the first method step is repeated with a respective other static voltage system, in particular with in each case other voltages which are constant in the other time segment. The advantage here is that with suitably different selected motor voltage space pointers a review of all stator windings is executable and thus a faulty check, for example, a non-checking one of the stator windings can be prevented. In addition, even by proper choice of the angles between the motor voltage space pointers, identifying the source of the error can be achieved.

Important features in the method for testing a drive are that the drive has an electric motor fed by an inverter,
wherein the electric motor has a rotor rotatably mounted relative to a stator,
wherein the stator has stator windings which are fed from a voltage system, that is to say a motor voltage space pointer, which is provided by the inverter at its AC-side connection,
in particular, wherein the voltage system is formed of voltages each feeding a respective one of the stator windings,
wherein in a first method step by means of the inverter at the AC-side terminal of the inverter in a first time period, a static motor voltage space pointer is provided and the associated, stationary adjusting motor current space pointer is determined,
wherein at least one resistance value is determined from the motor voltage space vector and the motor current space vector, in particular according to Ohm's law,
wherein the resistance value is monitored for impermissibly high deviation from a reference value, in particular, and when the inadmissibly high deviation is exceeded, warning information is displayed and / or passed on,
wherein in at least one further method step, the first method step is repeated in each case with a respectively different static motor voltage space vector, in particular in a respective other period of time.

The advantage here is that the drive can be tested in a simple manner without additional resources. In this case, the frequency converter which is present anyway can be used, which provides the motor with a voltage and detects and / or determines the current caused thereby. Because the underlying inventive idea is that a static, so temporally immutable motor voltage space pointer is provided. Thus, the inverter of the inverter at its Weichselspannungsseitigen connection provides three static potentials, which are referred to the mass or a zero potential as three voltages. Since these potentials are static, that is, they are fixed in time over a first period of time, a motor current space vector appears after a transient, whereby the rotor is preferably demagnetized and / or not rotated relative to the stator. Particularly advantageous so the brake has fallen.

In an advantageous embodiment, a brake of the motor remains activated during the process steps, so it has come to mind. The advantage here is that the test without interference sources, such as induced by a rotating rotor voltages is executable. Preferably, therefore, the brake is controlled in such a way that it is activated during the method steps for determining the resistance value, that is to say it has fallen inward. If the test results in no error, the brake for release in the subsequent controlled operation, ie a subsequent last step, released. However, if the test results in errors, ie an inadmissibly high deviation from a reference value, the brake continues to be activated, that is to say it has come in. Activation of the brake is preferably understood to mean the de-energized state in which the brake linings are pressed by a spring element against a braking surface and / or an armature disk and thus braking force is generated.

In an advantageous embodiment, the motor voltage space pointer of the respective further method step has an angular amount of 120 ° to the motor voltage space pointer of the preceding method step, in particular wherein each motor voltage space pointer differs from the other motor voltage space pointer, ie in particular the motor voltage space pointer are each pairwise different,
in particular, wherein a total of three method steps are carried out. The advantage here is that the stator windings of a three-phase motor are completely tested.

In an advantageous embodiment, the voltage applied to the DC voltage side terminal of the inverter DC voltage is determined to determine the motor voltage space pointer and determined from this, taking into account the pulse width modulation ratios of the drive signals for semiconductor switches of the inverter of the motor voltage space pointer. The advantage here is that a simple determination of the motor voltage space pointer is executable. In addition, such a determination is carried out in controlled operation, so that no special effort for the determination is necessary but the appropriate hardware and software parts are used.

In an advantageous embodiment, the controlled operation is carried out as a further subsequent last process step, that is, a non-static motor voltage space pointer is provided at the AC-side terminal of the inverter. The advantage here is that a three-phase voltage system is provided at the AC-side terminal of the inverter, so that the motor can be set in rotary motion.

Important features of the drive for carrying out an aforementioned method are that the drive has a means for determining the motor voltage and the motor current,
the drive having means for determining the resistance associated with the means for determining the motor voltage and the motor current,
wherein a means for monitoring for excessively large deviation of the resistance value from a reference value is connected to the means for determining the resistance.

The advantage here is that the means for the controlled operation of the engine anyway available means are used, so that no additional funds is necessary. It is only necessary that the inverter provides DC voltages, ie a static voltage system, at its AC-side output. Thus, the self-adjusting current can be detected and determined in a simple manner. From this, a resistance value is determined, which is monitored and closed from the determined resistance to any errors.

In an advantageous embodiment, by means of, in particular by means of a sensor, the angular position of the rotor is detected and monitored during execution of the method steps to standstill,
In particular, therefore, the angular position is monitored for an impermissible degree of deviation from a first angular position value. The advantage here is that it is ensured by means of an angular position sensor that the resistance measurement is not distorted by rotational movement of the rotor.

In an advantageous embodiment, the electric motor has an electromagnetically operable, controllable by the inverter brake,
wherein the method steps are carried out after each particular activation of the brake. The advantage here is that it is reliably ensured that no unintentional rotation of the rotor occurs.

Further advantages emerge from the subclaims. The invention is not limited to the combination of features of the claims. For the skilled person, further meaningful combination options of claims and / or individual claim features and / or features of the description and / or figures, in particular from the task and / or by posing the task by comparison with the prior art task.

The invention will now be described with reference to FIG 1 explained in more detail:

The drive according to the invention has an electric motor 1 with a stator having stator windings forming a rotating field winding.

The stator windings are the AC-side connection of an inverter 2 fed, at the Gleichspannungsseitigem terminal a DC voltage, in particular a DC link voltage, is applied.

Preferably, this DC voltage is provided by a rectifier, which is supplied at its mutual connection from a supply network.

The inverter has semiconductor switches arranged in half bridges, which can be controlled in a pulse-width-modulated manner. The pulse width modulated drive signals are supplied by a signal electronics to the control inputs of the semiconductor switches.

Thus, it is now possible to provide a three-phase voltage system to the motor. For this purpose, the inverter has three half-bridges connected in parallel, in particular three series circuits connected in parallel. Each of the half bridges, in particular series circuits, has two series-connected controllable semiconductor switches. By means of suitable control signals for the semiconductor switch is thus a rotating voltage ready adjustable for supplying the stator ready adjustable. However, other three-phase voltage systems can also be provided since, depending on the drive signals for the semiconductor switches of one of the half bridges, in particular series circuits, an arbitrary voltage value can be provided as long as it is between zero volts and the value of the DC voltage.

According to the invention, the stator windings form a rotating field winding. Thus, when the motor is energized with rotary voltage, a magnetic field space vector rotating at the frequency of this rotational voltage can be generated in the interior of the stator to which the rotor is exposed. The rotor has a short-circuit cage and / or permanent magnets. Thus, the motor is then rotated.

The three-phase voltage system is preferably multi-phase, for example three-phase. Each phase of the three-phase voltage system feeds a respective stator winding. The rotating field winding has a discrete rotational symmetry that at an imaginary rotation of 360 ° / N, where N is the number of pole pairs of the motor, each of the stator windings passes into another of the stator windings or in itself.

• - Windungsschluss, insbesondere also eine unzulässige elektrische Verbindung zweier Statorwicklungen vorliegt,
• - Kabelbruch, insbesondere also eine elektrische Leitung defekt ist,
• - Lockere Anschlüsse, insbesondere ein Wackelkontakt im Bereich des Anschlusskastens des Motors und/oder im Bereich des Frequenzumrichters vorliegt,
• - Defekt oder Öffnung eines Motorschützes 3,
• - Defekt einer zwischen Wechselrichter und Stator angeordneten Ausgangsfiltereinheit und/oder Ausgangsdrossel
• - und/oder Defekt eines Motorschutzschalters

vorliegt.According to the invention, a test is first carried out before this regular operation. It should be checked if there is an error, such as

• - Windungsschluss, in particular therefore an impermissible electrical connection of two stator windings,
• Cable break, in particular an electrical line is defective,
• Loose connections, in particular a loose contact in the region of the connection box of the motor and / or in the area of the frequency converter,
• - Defective or opening of a motor contactor 3 .
• Defect of an output filter unit and / or output choke arranged between inverter and stator
• - and / or defect of a motor protection switch

is present.

By means of the motor contactor 3 is the inverter 2 from the engine 1 severable.

In order to carry out the test, in the first step the stator windings are energized in such a way that a static magnetic field is generated which is aligned in a first direction, ie a magnetic field space pointer oriented substantially in the first direction, to which the rotor is exposed.

In this case, a voltage is generated by the inverter for a first period of time, wherein the time period is greater so the settling time required by the engine. The steady-state current value that is set in each of the motor phases is recorded. The voltage value is also detected. For this purpose, either with a sensor for detecting the output voltage, this is detected directly or the DC voltage is detected and determined by means of the present pulse width modulation ratio applied to the respective motor phase voltage. From the voltage applied to the motor phase and from the respectively detected current value, a resistance value is determined, which is monitored for exceeding or falling below threshold values, ie for exceeding an allowable deviation from a reference value.

Thereafter, in a second step, the 120 ° rotated static magnetic field space pointer is generated and the described determination and monitoring of the resistance value repeated.

In a third step, the described determination and monitoring of the resistance value is repeated again at a further 120 ° further rotated magnetic field space pointer.

In this way, the presence of a defect or defect is recognizable.

In another embodiment, it is not compared to a reference value but three resistance values to their deviation from one another. Ideally, they would all be the same.

For this purpose, in a first step, the potential + u is applied in a first motor phase, the potential -u / 2 is applied to the second and third motor phases, and the current i_u is measured, so that the resistance RS_u can be determined according to u / i_u.

Then, in a second step, the potential + u is applied in the second motor phase, the potential -u / 2 is applied to the first and third motor phases, and the current i_v is measured, so that the resistance RS_v can be determined according to u / i_v.

$$\frac{1}{R_{wu}}=\frac{1}{3R{S}_w}-\frac{1}{3R{S}_v}+\frac{1}{3R{S}_u}$$

$$\frac{1}{R_{uv}}=\frac{1}{3R{S}_u}-\frac{1}{3R{S}_w}+\frac{1}{3R{S}_v}$$

Then, in a third step, the potential + u is applied in the third motor phase, the potential -u / 2 is applied to the second and third motor phases, and the current i_w is measured, so that the resistance RS_w can be determined according to u / i_w. From this, the resistances of the delta connection are determined according to: $$\frac{1}{R_{vw}}=\frac{1}{3R{S}_v}-\frac{1}{3R{S}_u}+\frac{1}{3R{S}_w}$$

$$\frac{1}{R_{wu}}=\frac{1}{3R{S}_w}-\frac{1}{3R{S}_v}+\frac{1}{3R{S}_u}$$

$$\frac{1}{R_{uv}}=\frac{1}{3R{S}_u}-\frac{1}{3R{S}_w}+\frac{1}{3R{S}_v}$$

$$R_v=\frac{R_{uv}\ast R_{vw}}{R_{uv}+R_{vw}+R_{wu}}$$

$$R_w=\frac{R_{vw}\ast R_{wu}}{R_{uv}+R_{vw}+R_{wu}}$$

The three resistances of the delta connection result in the three winding resistances of the star connection: $$R_u=\frac{R_{uv}*R_{wu}}{R_{uv}+R_{vw}+R_{wu}}$$

$$R_v=\frac{R_{uv}*R_{vw}}{R_{uv}+R_{vw}+R_{wu}}$$

$$R_w=\frac{R_{vw}*R_{wu}}{R_{uv}+R_{vw}+R_{wu}}$$

To evaluate the symmetry of the motor, the quotient of maximum and minimum resistance is used. $$VerHältnis=\frac{Max\left(R_u.R_v.R_w\right)}{Min\left(R_u.R_v.R_w\right)}$$

If this ratio is greater than the specification, in particular as the default of 1.2, the engine is considered defective. Instead of the value 1,2, other values between 1, 1 and 1.5 can also be used advantageously.

Preferably, it is ensured during the resistance determination by activating a brake and / or by monitoring the angular position that the rotor does not perform any rotational movement. Thus, on the one hand, the accuracy of the determination is ensured and on the other hand improves the safety in the system comprising the engine or machine.

LIST OF REFERENCE NUMBERS

1

electric motor

2

inverter

3

motor contactor

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 112014003571 T5 [0003]
• EP 2933647 A1 [0004]

Claims (10)

A method of testing a drive, the drive comprising an electric motor powered by an inverter, the electric motor having a rotor rotatably mounted relative to a stator, the stator having stator windings fed from a voltage system provided by the inverter at its AC side terminal is provided, in particular wherein said voltage system is formed from voltages, which each feed a respective one of the stator windings, characterized in that a first static voltage system in a first process step by means of the inverter on the AC voltage side terminal of the inverter (+ V, -V / 2, -u / 2), in particular in a first time period constant voltages, are provided for feeding the stator windings and in each case detects the stationary adjusting value of the current flowing through a respective stator winding current, in particular determines, wobe i is determined from the voltage system, in particular from the respectively provided voltage and the values, at least a first resistance value, in particular according to the Ohm's law RS_u = u / i_u, in a second method step by means of the inverter at the AC voltage side connection of the inverter a second one static voltage system (-u / 2, + u, -u / 2), in particular in a first period constant voltages are provided for feeding the stator windings and in each case detects the stationary adjusting value of the current flowing through a respective stator winding current, in particular determined is, wherein from the second voltage system, in particular from the respective provided voltage and the values, at least a second resistance value is determined, in particular according to the Ohm's law RS_v = u / i_u, in a third method step by means of the inverter at the AC-side terminal of the inverter e in the third static voltage system (-u / 2, -u / 2, + u), in particular in a first time period, constant voltages are provided for feeding the stator windings and in each case the stationary value of the current flowing through a respective stator winding is detected, is determined in particular, wherein from the third voltage system, in particular from the respective provided voltage and the values, at least a third resistance value is determined, in particular according to the Ohm's law RS_W = u / i_W, wherein thereafter from the first, second and third resistance value other resistance values (R_u, R_v, R_W) are determined, in particular according to $$\frac{1}{R_{vw}}=\frac{1}{3R{S}_v}-\frac{1}{3R{S}_u}+\frac{1}{3R{S}_w}$$

$$\frac{1}{R_{wu}}=\frac{1}{3R{S}_w}-\frac{1}{3R{S}_v}+\frac{1}{3R{S}_u}$$

$$\frac{1}{R_{uv}}=\frac{1}{3R{S}_u}-\frac{1}{3R{S}_w}+\frac{1}{3R{S}_v}$$

wherein then a ratio is formed, in particular according to $$VerHältnis=\frac{Max\left(R_u.R_v.R_w\right)}{Min\left(R_u.R_v.R_w\right)}$$

wherein the ratio is monitored for impermissibly high deviation from a desired value, in particular a value from the range between 1.1 to 1.5, in particular 1.2, in particular and when exceeding the impermissibly high deviation warning information is displayed and / or weiterleitleitet. Method according to Claim 1 , characterized in that instead of monitoring the ratio of each resistance value to impermissibly high deviation from a reference value is monitored, in particular and when exceeding the impermissibly high deviation warning information is displayed and / or weiterverleitet. Method according to Claim 1 or 2 , characterized in that by means of, in particular by means of a sensor, the angular position of the rotor is detected and monitored during execution of the method steps to standstill, ie in particular the angular position is monitored for an impermissible degree of deviation from a first angular position value. Method according to one of Claims 1 to 3 , characterized in that the electric motor has an electromagnetically operable, controllable by the inverter brake, wherein the method steps are carried out after each particular activation of the brake. A method of testing a drive, the drive comprising an electric motor powered by an inverter, the electric motor having a rotor rotatably mounted relative to a stator, the stator having stator windings fed from a voltage system, ie motor voltage space vector, which is supplied by the motor Inverter is provided at its AC side terminal, in particular wherein the voltage system is formed of voltages, each feeding a respective one of the stator windings, characterized in that in a first step by means of the inverter at the AC side terminal of the inverter in a first period of time, a static motor voltage space pointer ready is determined and the associated, stationary adjusting motor current space pointer is determined, wherein from the motor voltage space pointer and the motor current space pointer at least one resistance value is determined, in particular according to Ohm's law, wherein in at least one further process step, the first process step is repeated in each case with another static motor voltage space pointer, in particular in a respective other period of time, wherein from the determined resistance values, a ratio is formed which is at un permissible high deviation from a reference value is monitored, in particular and when the impermissibly high deviation is exceeded, warning information is displayed and / or passed on, Method according to one of the preceding claims, characterized in that during the process steps, a brake of the motor remains activated, that is sunken. Method according to one of the preceding claims, characterized in that the motor voltage space pointer of the respective further process step has an angular amount of 120 ° to the motor voltage space pointer of the preceding method step, in particular wherein each motor voltage space pointer differs from the other motor voltage space pointer, in particular so the motor voltage space pointer are each pairwise different, in particular, wherein a total of three method steps are carried out. Method according to one of the preceding claims, characterized in that for determining the motor voltage space pointer which is applied to the DC voltage side terminal of the inverter DC voltage is determined and determined taking into account the pulse width modulation ratios of the drive signals for semiconductor switches of the inverter, the motor voltage space pointer. Method according to one of the preceding claims, characterized in that as a further subsequent final step of the controlled operation is carried out, that is, a non-static motor voltage space pointer on the AC-side terminal of the inverter is provided. Drive for carrying out a method according to one of the preceding claims, characterized in that the drive has a means for determining the motor voltage and the motor current, wherein the drive has a means for determining the resistance, which with the means for determining the motor voltage and the motor current is connected, wherein a means for monitoring an excessively large deviation of the resistance value of a reference value is connected to the means for determining the resistance.

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