Five-Phase PM Synchronous Motor Drive

Implement five-phase permanent magnet synchronous motor vector control drive

Library

Simscape / Electrical / Specialized Power Systems / Electric Drives / AC Drives

Description

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)

Remarks

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.

Parameters

General

Output bus mode

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.

Model detail level

Select between Detailed (default) and Average inverter models.

Mechanical input

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:

$$T_e=J\frac{d}{dt}{\omega }_r+F{\omega }_r+T_m$$

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.

See Mechanical Coupling of Two Motor Drives.

Use signal names as labels

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.

Permanent Magnet Synchronous Machine Tab

The Electrical parameters and the Mechanical parameters sections display the parameters of the Synchronous Machine block.

Converters and DC Bus Tab

Rectifier

The Rectifier section of the Converters and DC bus tab displays the parameters of the Universal Bridge block.

DC Bus

Capacitance

Specify the DC bus capacitance, in farads. Default is 2000e-6.

Braking Chopper Section

Resistance

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.

Chopper frequency

Specify the braking chopper frequency, in hertz. Default is 4000.

Activation voltage

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.

Shutdown voltage

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

Inverter

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.

Source frequency

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.

On-state resistance

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.

Controller Tab

Regulation type

Specify the type of regulation, Speed regulation (default) or Torque regulation.

Schematic

Open a diagram showing the speed and vector controllers schematics.

Speed Controller Section

Acceleration

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.

Deceleration

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.

Speed cutoff frequency

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.

Speed controller sampling time

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.

Proportional gain

Specify the speed controller proportional gain. This parameter is used only in speed regulation mode. Default is 0.5.

Integral gain

Specify the speed controller integral gain. This parameter is used only in speed regulation mode. Default is 40.

Negative

Specify the maximum negative torque, in newton-meters, applied to the motor by the vector controller (N.m). Default is -35.

Positive

Specify the maximum positive torque, in newton-meters, applied to the motor by the vector controller. Default is 35.

Vector Control Section

Sampling time

Specify the vector controller sampling time, in seconds. The sampling time must be a multiple of the simulation time step. Default is 20e-6.

Current controller hysteresis band

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.

Maximum switching frequency

Specify the maximum inverter switching frequency, in hertz. Default is 20e3. This parameter is ignored when using the average-value inverter.

Inputs and Outputs

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.

Model Specifications

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)

Examples

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.

References

[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.