DE102017008380A1 - A system comprising a first inverter and a second inverter - Google Patents

Abstract

A system comprising a first inverter feeding a first electric motor and a second inverter feeding a second electric motor, wherein the DC side terminal of the first inverter is connected to the DC side terminal of a rectifier supplied from an AC electric power supply network, the DC side terminal of second inverter is connected to the DC voltage side terminal of the rectifier, in particular wherein the two DC side terminals of the inverter are connected in parallel, wherein a controller, in particular in the first inverter, is provided, which received by the first inverter at the DC side terminal and detected current (I_ZK_SMS_ist ) is regulated to a desired value (I_ZK_SMS_Soll) in that the torque of the first electric motor fed by the first inverter is manipulated variable.

Description

The invention relates to a system comprising a first inverter and a second inverter.

It is well known that an inverter feeds an electric motor and can be supplied by a rectifier at its DC side terminal.

From the DE 10 2006 033 562 B3 For example, a servo-press with power management is known as the closest prior art. In this case, a plurality of electric motor-driven load machines are disclosed, which have high intermittent power fluctuations and are therefore operated via Pulswechselrcihter on a fed from the grid and buffered via a rotating load memory DC voltage intermediate circuit.

From the DE 10 2010 023 536 A1 A method for intelligent drive-based network power regulation by kinetic energy storage is known.

From the EP 2 525 481 A1 a control device for a DC link converter is known.

From the DE 101 50 347 A1 is a heavy fan for three-phase motors in passenger installations known.

From the US 2013/0 126 276 A1 is known a control device for a lift.

From the DD 260 636 A3 a circuit arrangement for adaptive speed control of a balancing system is known.

The invention is therefore the object of developing a system, with the lowest possible power draw from an AC power supply network should be necessary.

According to the invention the object is achieved in the system according to the features indicated in claim 1.

Important features of the invention in the system, are that the system comprises a first inverter, which feeds a first electric motor, and a second inverter, which feeds a second electric motor,
wherein the DC side terminal of the first inverter is connected to the DC side terminal of a rectifier supplied from an AC electric power supply network,
wherein the DC side terminal of the second inverter is connected to the DC side terminal of the rectifier,
in particular wherein the two DC-side connections of the inverters are connected in parallel,
wherein a controller is provided, which regulates an actual value to a desired value by the torque of the first inverter supplied by the first electric motor is manipulated variable,
wherein the actual value is a measure of the power transmitted by the second inverter, in particular recorded, and the setpoint is a measure of the power to be transmitted by the first inverter,
and / or the actual value is the current absorbed or detected by the first inverter at its DC-side terminal.

The advantage here is that as little power is removed from the AC power supply network. Thus, when repeatedly alternating between regenerative and engine operation of the second electric motor of the first drive is used as flywheel mass storage and thus related less power from the AC power supply network via the rectifier.

In an advantageous embodiment, the first electric motor is designed as a fan motor, wherein the cooling air flow conveyed by the fan motor is guided along the second electric motor and / or second inverter and / or through the second electric motor,
in particular, where therefore a fan is rotatably connected to the rotor shaft of the first electric motor. The advantage here is that the fan is used as a flywheel. Thus, the fan motor is operated as flywheel mass storage.

In an advantageous embodiment, the cooling air flow increases in the regenerative operation of the second electric motor, in particular so it increases. The advantage here is that power can be supplied to the flywheel mass storage device during regenerative operation and thus the flywheel mass storage device designed as a fan motor absorbs more energy. Due to the higher speed thus a stronger air flow is generated, and thus the second inverter and / or the second electric motor cooled more.

In an advantageous embodiment, a means for calculating the difference determines the desired value (I_ZK_SMS_Soll) by forming the difference between a constant value (Const) and the detected value (I_ZK_App) of the current received by the second inverter at its DC-side terminal. The advantage here is that the constant value of the current drain from the AC power supply corresponds. Thus, the excess power is removed from the flywheel mass storage or discharged to him.

In an advantageous embodiment, the constant value (Const) is as small as possible, in particular in the averaged over a long period range. The advantage here is that the longest possible minimal current drain from the AC power supply network can be achieved. The duration of the period depends on the energy capacity limits of the flywheel mass storage. For example, a further energy removal with discharged energy storage, so flywheel energy storage, not feasible. Likewise, with maximum allowable charging a further power to the energy storage is no longer allowed. If the flywheel mass storage is dimensioned sufficiently large, the minimum current drain can be permanently realized.

In an advantageous embodiment, the housing of the first inverter also encloses the second inverter housing forming. The advantage here is that the most compact design is achievable. In addition, for example, a single signal electronics is sufficient for both inverters.

In an advantageous embodiment, a signal electronics generates the drive signals for the arranged in half-bridges power semiconductor switch of the first inverter and the drive signals for arranged in half-bridges power semiconductor switch of the second inverter. The advantage here is that a data bus is eliminated and thus generates a single signal electronics, the drive signals of both inverters.

In an alternative advantageous embodiment, a signal electronics of the first inverter is connected by means of a data bus with the signal electronics of the second inverter for data exchange. The advantage here is that by means of the data bus, the two signal electronics of the two inverters are synchronized operable and / or can exchange measured values and process variables. The two inverters can be arranged in separate housings.

In an advantageous embodiment, the controller has a superimposed speed controller, which regulates the first motor to a target speed. The advantage here is that a long-term running away the speed is avoidable and / or the compensation of the application cycle is not impaired.

In an advantageous embodiment, the superimposed speed controller has a greater time constant, in particular a time constant which is at least ten times greater, in comparison to the cycle time of the machine or system driven by the second motor. The advantage here is that a long-term runaway speed is avoidable.

In an advantageous embodiment, the setpoint speed is predetermined such that the actual speed of the first motor does not exceed a maximum value during generator operation of the second motor and that the speed of the first motor does not fall below a minimum value during motor operation of the second motor. The advantage here is that in the first motor by means of its rotatably connected to the rotor shaft flywheel, in particular fan, enough energy can be stored in the motor phase of the application, ie the second motor, this is fed, without the setpoint desired, predetermined maximum value of mains input power is exceeded.

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 posing by comparison with the prior art task.

The invention will now be explained in more detail with reference to figures:

In the 1 a first system according to the invention is shown.

In the 2 a control method applied there is shown schematically.

In the 3 another system according to the invention is shown.

As in 1 is shown, is from an AC power grid 1 a rectifier 2 supplies at its DC output two parallel inverters ( 3 . 4 ) are connected.

In this case, the DC-side output of the rectifier 2 , So the intermediate circuit, the voltage U_ZK on. The one from the inverter 3 taken current I_ZK_App is detected or determined. Likewise, that of the inverter 4 taken current I_ZK_SMS detected or determined.

The inverter 3 feeds one to the AC side output of the inverter 3 connected three-phase motor 5 , there instructs the inverter 3 a built-up of three half-bridges power amplifier, wherein in each upper and in each lower branch of each half-bridge in each case a power semiconductor switch, in particular IGBT or MOSFET, is arranged. The power semiconductor switches this power output stage of the inverter 3 are each driven by means of pulse width modulated signals, which of a signal electronics of the inverter 3 be generated. The signals from the signal electronics of the inverter 3 generated such that by the inverter 3 adjusted motor voltage of the motor current is regulated to a predetermined setpoint. The nominal value of the motor current corresponds at least approximately to a nominal value for torque.

The intermediate circuit voltage U_ZK is also at the DC voltage side connection of the inverter 4 on, which supplies an electric motor of a flywheel mass storage. In this case, the electric motor is preferably designed as a three-phase motor whose motor phase currents are referred to as I_U, I_V and I_W. The three-phase motor is preferably designed as an asynchronous motor.

The electric motor has a rotor shaft, which rotatably with a rotatably mounted flywheel 6 is connected, so that in the engine operation energy in the flywheel energy storage from the electric motor can be stored and can be removed in generator mode.

The inverter 4 So feeds one with the AC side output of the inverter 4 connected three-phase motor. In this case, the inverter points 4 likewise a power output stage constructed from three half-bridges, wherein a respective power semiconductor switch, in particular IGBT or MOSFET, is arranged in each upper and in each lower branch of each half-bridge. The power semiconductor switches this power output stage of the inverter 4 are each driven by means of pulse width modulated signals, which of a signal electronics of the inverter 4 be generated. The signals from the signal electronics of the inverter 4 generated such that by the inverter 4 adjusted motor voltage of the motor current is regulated to a predetermined setpoint. The nominal value of the motor current corresponds at least approximately to a nominal value for torque. Alternatively, it is also possible to control to a speed setpoint curve.

The signal electronics of the inverter 3 is with the signal electronics of the inverter 4 for data exchange via fieldbus 10 connected.

According to the invention is in 2 illustrated control method applied:
Here, the DC-side connection of the inverter 3 detected or determined current I_ZK_App made from the flywheel energy storage 9 supplied current I_ZK_SMS and the current supplied by the rectifier. In order for this current supplied by the rectifier does not exceed a constant value const, that of the flywheel energy storage 9 supplied current I_ZK_SMS regulated accordingly.

This is done according to 2 the detected or determined current value I_ZK_APP, which is reduced by the constant value const, is predefined as setpoint I_ZK_SMS_Soll to a controller to which the detected or determined actual value I_ZK_SMS is supplied. In this case, the controller is designed as a linear controller, in particular PI controller, the manipulated variable of the setpoint of the torque of the inverter 4 powered electric motor DR of the flywheel mass storage 9 is.

Thus, the electric motor DR of the flywheel mass storage 9 accelerated or decelerated so that the sum of its own load value and the transmitted load value of the second drive 8th , in particular of the electric motor 5 , the constant value, or at least regulated.

Thus, that of the electric motor 5 over the inverter 3 caused current drain from the rectifier 2 can be limited by adding a corresponding amount of electricity from the flywheel energy storage 9 is delivered.

As in 1 It can be seen on the flywheel 6 rotatably connected rotor arranged a fan, in particular so also rotatably connected to the rotor. In this way, the fan-assisted airflow is used to cool the drive 8th , especially the engine 5 and / or the inverter supplying it 3 , used.

Alternatively, the flywheel 6 can be realized by corresponding massive design of the fan. Thus, therefore, a driven by a motor fan is operated as a flywheel mass storage. In the 2 shown to apply control in such a fan motor, in particular also executable when the maximum power of the drive 8th less than the maximum power that can be picked up or released by the fan motor.

In any case, the storable at maximum speed of the fan in the flywheel energy storage is greater than the one-hundred-second operation of the fan with the maximum capacity. Preferably, the stored energy greater than the product of the capacity of the fan and a hundred seconds.

As in 3 shown is unlike the 1 a single signal electronics 32 a single inverter 33 shown with computer unit, which is a power amplifier 30 of the second inverter 30 and a power amplifier 31 of the first inverter 30 controls.

The housing of the inverter 33 surrounds both power output stages ( 30 . 31 ) as well as the signal electronics 32 ,

Each of the power output stages 30 and 31 has the arranged in each case three half bridges controllable power semiconductor switch, so that the respective motor can be fed.

In regenerative operation, the three-phase motor 5 from acting as a fan flywheel energy storage 9 intensified cooled because power to the flywheel mass storage 9 is dissipated and thus its speed increases.

By means of the control of both power output stages 30 and 31 through the same signal electronics 32 eliminates the need for a data bus connection between two separate inverters, such as between the in 1 shown converters 7 and 8th ,

In a further embodiment of the invention, a superimposed speed controller is present whose time constant is greater than the cycle time of the second motor driven application.

In an advantageous embodiment, the superimposed speed controller has a greater time constant, in particular a time constant which is at least ten times greater, in comparison to the cycle time of the machine or system driven by the second motor. The advantage here is that a long-term runaway speed is avoidable.

LIST OF REFERENCE NUMBERS

1

AC voltage supply network

2

rectifier

3

Inverter of the second drive 8th

4

Inverter of the first drive 7

5

Three-phase motor

6

Inertia

7

first converter, in particular inverter

8th

first drive

9

Flywheel energy storage

10

fieldbus

30

Power output stage of the second inverter 30 the inverter 33

31

Power output stage of the first inverter 30 the inverter 33

32

Signal electronics with computer unit

33

inverter 33 with housing

CPU

Signal electronics with computer unit

DR

Three-phase motor, in particular asynchronous motor

U_ZK

Intermediate circuit voltage

I_ZK

from the rectifier 2 in the intermediate circuit transmitting current

I_ZK_App

Actual value of the input current of the inverter 3

I_ZK_SMS

Actual value of the input current of the inverter 4

I_ZK_SMS_Soll

Setpoint of the input current of the inverter 4

I_U

first phase current of the motor DR

I_V

second phase current of the motor DR

I_w

third phase current of the motor DR

M_Soll

Torque setpoint as manipulated variable of the PI controller

const

Setpoint current, in particular from the rectifier 2 setpoint current recorded in the DC link

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 102006033562 B3 [0003]
• DE 102010023536 A1 [0004]
• EP 2525481 A1 [0005]
• DE 10150347 A1 [0006]
• US 2013/0126276 A1 [0007]
• DD 260636 A3 [0008]

Claims (15)

A system comprising a first inverter, which feeds a first electric motor, and a second inverter, which feeds a second electric motor, characterized in that the DC side terminal of the first inverter is connected to the DC side terminal of a supplied from an AC electrical mains rectifier, wherein the DC-side terminal of the second inverter is connected to the DC side terminal of the rectifier, in particular wherein the two DC side terminals of the inverter are connected in parallel, wherein a regulator is provided which hinregelt an actual value to a desired value by the torque of the first inverter fed by the first electric motor Manipulated variable is, the actual value is a measure of the transmitted from the second inverter, in particular recorded, power and the setpoint is a measure of the v is power to be transmitted from the first inverter, and / or the actual value (I_ZK_SMS_ist) is the current picked up or detected by the first inverter at its DC side terminal. System according to claim 1, characterized in that the first electric motor is designed as a fan motor, wherein the fan motor promoted cooling air flow on the second electric motor and / or second inverter along and / or passed through the second electric motor, in particular so where a fan rotatably with the rotor shaft of the first electric motor is connected. System according to at least one of the preceding claims, characterized in that the regenerative operation of the second electric motor, the cooling air flow increases, in particular thus increases. System according to at least one of the preceding claims, characterized in that a fan rotatably connected to the rotor shaft of the first electric motor, in particular wherein the fan is at least partially made of metallic material, in particular so that the fan is designed not only suitable for conveying a cooling air flow but as flywheel mass storage is effective, the energy stored in the flywheel energy storage is greater than the product of flow rate and one hundred seconds. System according to at least one of the preceding claims, characterized in that with the rotatably mounted part of the first motor, in particular with the rotor shaft of the first motor, another part, in particular a flywheel, is rotatably connected. System according to at least one of the preceding claims, characterized in that a means for subtraction determines the setpoint (I_ZK_SMS_Soll) by forming the difference of a constant value (Const) and the detected value (I_ZK_App) of the second inverter at its DC-side terminal absorbed current. System according to at least one of the preceding claims, characterized in that the constant value (Const) is as small as possible, in particular in the averaged over a long period range. System according to at least one of the preceding claims, characterized in that the housing of the first inverter surrounds the second inverter housing forming. System according to at least one of the preceding claims, characterized in that a signal electronics generates the drive signals for arranged in half bridges power semiconductor switch of the first inverter and generates the drive signals for arranged in half bridges power semiconductor switch of the second inverter wherein the signal electronics having the controller. System according to one of claims 1 to 7, characterized in that a signal electronics of the first inverter is connected by means of a data bus with the signal electronics of the second inverter for data exchange. System according to at least one of the preceding claims, characterized in that the controller has a superimposed speed controller, which regulates the first motor to a target speed. System according to at least one of the preceding claims, characterized in that the superimposed speed controller has a larger time constant, in particular at least ten times greater time constant, compared to the cycle time of the driven by the second motor machine or system, and / or the setpoint speed is predetermined such that the speed of the first motor does not exceed a maximum value during regenerative operation of the second motor and that during motor operation of the second motor a minimum speed does not fall below, and / or that as long as the speed, in particular actual speed, amount of the first motor in terms of magnitude exceeds a first value, in particular threshold value, the constant value (const) - monotonically decreasing depending on the time, in particular until the value zero is reached, System according to at least one of the preceding claims, characterized in that as long as the speed, in particular actual speed, the first motor in terms of absolute value falls below a second value, in particular threshold value, the constant value (const) monotonically increasing depending on the time, in particular is increased , in particular until the detected value (I_ZK_App) is reached or, in particular, to compensate for system losses up to a value greater than the detected value (I_ZK_App), wherein the magnitude of the second value is less than the magnitude of the first value. System according to at least one of the preceding claims, characterized in that the controller has a pilot control, which pre-controls the losses of the first inverter and motor or the complete idle losses of the system to relieve the regulator. System according to at least one of the preceding claims, characterized in that the controller has a predefinable gain and / or another predetermined parameter, the gain of the first inverter depending, in particular dynamically dependent, is adapted by the speed of the first motor, in particular to the Control, in particular power control, over a speed range, in particular optimally, to allow.

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