Implement five-phase permanent magnet synchronous motor vector control drive
The Five-Phase PM Synchronous Motor Drive (AC8) block represents a classical vector control drive for five-phase permanent magnet synchronous motors. This drive features a closed loop speed control based on vector control method. The speed control loop outputs the reference electromagnetic torque of the machine. The reference direct and quadrature (dq) components of the stator current corresponding to the commanded torque are derived based on vector control strategy. The reference dq components of the stator current are then used to obtain the required gate signals for the inverter through a hysteresis-band current controller.
The main advantage of this drive, compared to scalar-controlled drives, is its fast dynamic response. The inherent coupling effect between the torque and flux in the machine is managed through decoupling (stator flux orientation) control, which allows the torque and flux to be controlled independently. However, due to its computation complexity, the implementation of this drive requires fast computing processors or DSPs.
Note
The Five-Phase PM Synchronous Motor Drive block is commonly called the
AC8
motor drive.
The Five-Phase PM Synchronous Motor Drive block uses these blocks from the Electric Drives / Fundamental Drive Blocks library:
Speed Controller (AC)
Vector Controller (PMSM)
DC Bus
Inverter (Five-Phase)
The control system has two different sampling times: the speed controller sampling time and the vector controller sampling time.
The speed controller sampling time must be a multiple of the vector controller sampling time and a multiple of the simulation time step. The average-value inverter model has lower time constants, compared to the detailed converter model. Therefore, you can use higher simulation time steps with this type of model. For a vector controller sampling time of 30 μs, good simulation results have been obtained for a simulation time step of 30 μs.
The simulation time step must be lower than the vector controller time step.
The stator currents id1*, iq2*, and id2* are set to 0 inside the vector controller block since only the iq1 current contributes to torque production.
Select how the output variables are organized. If you select Multiple
output buses
(default), the block has three separate output buses for motor,
converter, and controller variables. If you select Single output
bus, all variables output on a single bus.
Select between Detailed
(default) and
Average
inverter models.
Select between Torque Tm
(default), Speed
w
, and the mechanical rotational port
as the
mechanical input.
When you select Torque Tm
, the block outputs the motor speed
according to the following differential equation, describing the mechanical system
dynamics:
This mechanical system is modeled inside the Synchronous Machine block.
When you select Speed w
as the mechanical input, the block outputs
the electromagnetic torque, allowing you to model the mechanical system dynamics outside the
Five-Phase PM Synchronous Motor Drive block. With this setting, the inertia
and viscous friction parameters do not appear in the mask of the block.
When you select mechanical rotational port
, the block shows
the connection port S, which counts for the mechanical input and output. It allows a direct
connection to the Simscape™ environment. The mechanical system of the motor is modeled inside the drive and
is based on the same differential equation.
When you select this check box, the Motor
, Conv
,
and Ctrl
measurement outputs use the signal names to identify the bus
labels. Select this option for applications that require bus signal labels to have only
alphanumeric characters.
When this check box is cleared (default), the measurement output uses the signal definition to identify the bus labels. The labels contain nonalphanumeric characters that are incompatible with some Simulink® applications.
The Electrical parameters and the Mechanical parameters sections display the parameters of the Synchronous Machine block.
The Rectifier section of the Converters and DC bus tab displays the parameters of the Universal Bridge block.
Specify the DC bus capacitance, in farads. Default is
2000e-6
.
Specify the braking chopper resistance, in ohms. Use this resistance to avoid bus
overvoltage during motor deceleration or when the load torque tends to accelerate the motor.
Default is 8
.
Specify the braking chopper frequency, in hertz. Default is
4000
.
The dynamic braking is activated when the bus voltage reaches the upper limit of the
hysteresis band. Default is 320
. The figure Chopper Hysteresis Logic shows the braking chopper hysteresis logic.
Specify the shutdown voltage, in volts. This value is the point at which the dynamic
braking shuts down when the bus voltage reaches the lower limit of the hysteresis band.
Default is 310
. The chopper hysteresis logic is shown in the following
figure.
Chopper Hysteresis Logic
The Inverter section of the Converters and DC bus tab displays the parameters of the Universal Bridge block that is included in the Power Electronics library of the Fundamental Blocks library.
Specify the frequency of the voltage source, in hertz. Default is
60
. The Source frequency parameter is available only
when the Model detail level parameter is set to
Average
.
Specify the on-state resistance of the inverter devices, in ohms. Default is
1e-3
. The On-state resistance parameter is
available only when the Model detail level parameter is set to
Average
.
Specify the type of regulation, Speed regulation
(default) or
Torque regulation
.
Open a diagram showing the speed and vector controllers schematics.
Specify the maximum acceleration allowed for the motor, in rpm/s. An excessively large
positive value can cause DC bus undervoltage. This parameter is used only in speed
regulation mode. Default is 1000
.
Specify the maximum change of speed allowed during motor deceleration, in rpm/s. An
excessively large negative value can cause DC bus overvoltage. This parameter is used only
in speed regulation mode. Default is -1000
.
Specify the speed measurement first-order low-pass filter cutoff frequency, in hertz.
This parameter is used only in speed regulation mode. Default is
250
.
Specify the speed controller sampling time, in seconds. The sampling time must be a
multiple of the simulation time step. Default is 4*20e-6
.
Specify the speed controller proportional gain. This parameter is used only in speed
regulation mode. Default is 0.5
.
Specify the speed controller integral gain. This parameter is used only in speed
regulation mode. Default is 40
.
Specify the maximum negative torque, in newton-meters, applied to the motor by the
vector controller (N.m). Default is -35
.
Specify the maximum positive torque, in newton-meters, applied to the motor by the
vector controller. Default is 35
.
Specify the vector controller sampling time, in seconds. The sampling time must be a
multiple of the simulation time step. Default is 20e-6
.
Specify the current hysteresis bandwidth, in amperes. Default is
0.1
. This value is the total bandwidth distributed symmetrically around
the current set point. The following figure shows a case where the current set point is Is*
and the current hysteresis bandwidth is set to dx
.
This parameter is ignored when using the average-value inverter.
Note
A Rate Transition block is needed to transfer data between different sampling rates. This block causes a delay in the gate signals, so the current might exceed the hysteresis band.
Specify the maximum inverter switching frequency, in hertz. Default is
20e3
. This parameter is ignored when using the average-value
inverter.
SP
Outputs the speed or torque set point. The speed set point can be a step function, but the speed change rate follows the acceleration and deceleration ramps. When the load torque and the speed have opposite signs, the accelerating torque is the sum of the electromagnetic and load torques.
Wm
, Tm
, or S
The mechanical input of the drive: motor speed (Wm), mechanical torque (Tm), or mechanical rotational port (S).
A, B, C
The three phase terminals of the motor drive.
When the Output bus mode parameter is set to Multiple output buses, the block has the following three output buses:
Motor
The motor measurement vector. This vector allows you to observe the motor's variables using the Bus Selector block.
Conv
The five-phase converter measurement vector. This vector contains:
The DC bus voltage
The rectifier output current
The inverter input current
You can visualize all current and voltage values of the bridges using the Multimeter block.
Ctrl
The controller measurement vector. This vector contains:
The torque reference
The speed error (difference between the speed reference ramp and actual speed)
The speed reference ramp or torque reference
When the Output bus mode parameter is set to Single output bus, the block groups the Motor, Conv, and Ctrl outputs into a single bus output.
The library contains a 4.4 kW drive parameter set. The table shows the specifications of the 4.4 kW drive.
Drive Input Voltage: | |
Amplitude | 160 V (L-L) |
Frequency | 60 Hz |
Motor Nominal Values: | |
Power | 4.4 kW |
Speed | 900 rpm |
Voltage | 160 V (L-N) |
The ac8_example
model shows the simulation of the
Five-Phase PM Synchronous Motor Drive block under standard load condition. The
ac8_example_simplified
model shows the simulation of the average-value model
under the same load conditions.
[1] Bose, B. K. Modern Power Electronics and AC Drives. Upper Saddle River, NJ: Prentice-Hall, 2002.
[2] Krause, P. C. Analysis of Electric Machinery. New York: McGraw-Hill, 1986.
[3] Toliyat, H. A. Analysis and Simulation of Multi-Phase Variable Speed Induction Motor Drives Under Asymmetrical Connections. Applied Power Electronics Conference and Exposition, Vol. 2, 1996, pp. 586–592.
[4] Beaudart, F., F. Labrique, E. Matagne, D. Telteux, and P. Alexandre. Control under normal and fault tolerant operation of multiphase SMPM synchronous machines with mechanically and magnetically decoupled phases. International Conference on Power Engineering, Energy and Electrical Drives, 2009, pp. 461–466.