A permanent magnet N-S may be located at the center. The DQ reference frame of the D-axis 16 and Q-axis 18 is fixed to the rotor of the motor. The axis of the field winding in the direction of the DC field is called the rotor direct axis, or the d-axis. The axis that is 90 degrees later than the d-axis is the quadrature axis q-axis. R, S, T. The transformation uses the three-phase signals shown in FIG. The user can configure which method to use based on the motor controller design.
In one embodiment, the system will allow the user to select whether to use the equation aligning with the q-axis or the d-axis as the measurement configuration. This transformation will allow the users to operate on the stator circuit voltage equation and transform it to the q-d-O coordinates.
The PLL is generally embedded in the controller circuit of the three-phase motor. This method emulates a hardware PLL of the controller circuit using a software PLL to adjust the Phase shift and delays introduced from the filters. If PLL is already implemented in motor controller circuit hardware, then acquired three-phase signals has the effect of this. The user can choose to apply software PLL, so that one can perform in the measurement flow and replicate a hardware PLL.
This is configurable in the measurement. This axis is configurable in the measurement as source input. Another approach is referred to as the Standard method. This represents the fixed rotor angle of the synchronous machines. This is called as freewheeling theta method. The user can then use this theta value and compute DQ0 at every sample point. In the PLL method one can regulate direct or quadrature axis to zero, unlike in the freewheeling method above.
The standard method is simplest of all because it relies on the hardware implementation for synchronization. Further, under balanced conditions, the value along the Z-axis is zero, and therefore produces no flux at all.
This allows the d-q transformation to simplify to equation 7 :. In this equation 7 , referred to as the DQ0 or forward equation, K is a constant. This causes the magnitude of the D-Q quantities to be equal to that of the three-phase quantities. For example, interpretation of K may differ. In the embodiments here, the DQ0 transformation takes as its inputs the three-phase R-S-T time-domain voltages and currents from the motor drive input. The inverse transformation uses the DQ0 signals computed by the motor controller as its inputs to get the R-S-T values, as shown below:.
The motor receives power inputs from the main AC supply at the drive input These filtered and buffer signals are then converted back to AC and reach the motor and drive train In a typical system, the designers could theoretically attempt to sample, e.
However, this approach is impractical because it is extremely difficult to physically reach these signal access points with a probe. Therefore, rather than trying to reach these signal access points, a typical approach involves providing an external stimulus to the controller, measuring the controller input signals, and capturing the output of the analog-to-digital converter ADC 32 in the controller. However, as previously mentioned, this typical approach also involves using an FPGA to produce the stimulated signals, and sensors to capture the data, e.
In contrast, the embodiments here capture the actual in-circuit signals and allow the controller to generate the DQ0 transformed signals from these signals. The embodiments provide more accurate signal measurements and a much less complex solution by having the controller operate on the in-circuit signals. The system captures these signals using connections at either the drive input, as shown at 28 , or at the output of the drive and drive output 22 , as shown at In either case, these signals will comprise analog three-phase signals R, S, T.
Either or both voltage and current three-phase signals may be captured by using, for example, appropriate voltage probes and current probes, respectively. The controller 26 receives the analog three-phase signals The controller then executes instructions to calculate the DQ0 transformation discussed above, using the forward equation.
One can apply the transformation equations to the voltage and current three-phase signals separately and get the DQ0 for voltage and the DQ0 for current. The DQ0 signals 35 can be provided back to the device under test as feedback. The three-phase analog signals at 30 include this feedback. As understood by those skilled in the art, the controller 26 may also include a PWM circuit 34 , providing gate drive signals to the drive and drive output 22 , as shown.
Typically, the probe interface may be one or more connectors to a cable. The interface 42 includes appropriate circuitry not shown for acquiring the three-phase signals, which may include signal conditioning circuitry, analog-to-digital converters, memories, etc. The processor 44 measures performance of the device under test based on the DQ0 signals.
The processor 44 may also perform an inverse DQ0 transformation and produce reconstructed three-phase signals based on DQ0 signals.
The device may also include a memory 46 for storing both instructions executed by the processor to cause it to perform the transformations, and for storing data. The device may also include a display 48 to allow the device to display the data, as discussed below. The device may also include a user interface 49 for receiving configuration settings from a user.
The measurement allows configuration for initial alignment of Phase A with the d-axis or with the q-axis. A user can see the change in the output results and Phasor plot based on the configuration.
One should note that the brushless DC motor of these examples merely provides examples of the input and resulting signals and no limitation to that particular device under test. Application of the backwards, inverse DQ0 transform results in the three-phase waveforms shown in FIG. Usually, however, the user will want to see the inverse transform to monitor performance of the controller As discussed previously, the three-phase signals vary in time, which means that no steady state operation point exists.
Referring back to FIG. The DQ0 transformation results in the elimination of all time-varying inductances in the three-phase voltage and current signals as shown in FIG. In FIG. The a-axis and d-axis overlap at the 0 axis at The b-axis is shown at The c-axis is at 47 , and the q-axis is at The zero axis is fixed at 62 , with the a-axis and the d-axis overlapping at The q-axis is at 64 , the b-axis is at 66 , and the c-axis is at The sample rate has been simulated to show the rotating part, although in an actual plot the rate can be much slower.
This is an indicative example of the rotating vectors. The plot update rate is equivalent to product of the frequency of the 3-phase RST signals and number of such cycles in the acquisition. The method starts at 70 for the forward transform, where the system acquires analog three-phase signals.
The system can acquire either or both voltage and current analog three-phase signals. At 71 , the DQ0 transform is computed using the acquired analog three-phase signals. This measurement system does not introduce any delay, but, unlike the Fourier analysis done in the Sequence Analyzer block, it is sensitive to harmonics and imbalances.
Connect to the first input the vectorized sinusoidal phase signal to be converted [phase A phase B phase C]. The output is a vectorized signal containing the three sequence components [d q o], in the same units as the abc input signal. Analysis of Electric Machinery. New York: McGraw-Hill, , p. Choose a web site to get translated content where available and see local events and offers.
Based on your location, we recommend that you select:. Select the China site in Chinese or English for best site performance. Other MathWorks country sites are not optimized for visits from your location. Toggle Main Navigation. In analysis of three-phase synchronous machines the transformation transfers three-phase stator and rotor quantities into a single rotating reference frame to eliminate the effect of time-varying inductances.
A high-voltage battery feeds the HESM through a controlled three-phase converter for the stator windings and through a controlled four quadrant chopper for the rotor winding. Select a Web Site Choose a web site to get translated content where available and see local events and offers. The total simulation time t is 0. As an example, the DQZ transform is often used in order to simplify the analysis of three-phase synchronous machines or to simplify calculations for the control of three-phase inverters.
By using this site, you agree to the Terms of Use and Privacy Policy. In electric systems, very often the ABand C values are oscillating in such a way that the net vector is spinning. This page has been translated by MathWorks. This type of Park transformation is also known as the sine-based Park transformation. As things are written above, the norm of the Clarke transformation matrix is still 1, which means that it only rotates an ABC vector but does not scale it.
The internal combustion engine ICE is represented by basic mechanical blocks. Springer India,p. Views Read Edit View history. In other projects Wikimedia Commons. Of course, it makes sense to only calculate co and si once if both the Park and inverse Park transforms are going to be used.
For computational efficiency, it makes sense to keep the Clarke and Park transforms separate and not combine them into one transform. The EM Controller subsystem includes a multi-rate PI-based cascade control structure which has an outer voltage-control loop and two inner current-control loops.
Actually, a forwards rotation of the reference frame is identical to a negative rotation of the vector. All Examples Functions Blocks More. The X component becomes the D component, which is in direct alignment with the vector of rotation, and the Y component becomes the Q component, which is at a quadrature angle to the direct component. At this point, the Z axis is now orthogonal to the plane in which any ABC vector without a common-mode component can be found.
0コメント