According to most motor & appliances manufacturers, improving the efficiency and the safety of appliances & embedded systems are now the key goals. Electronically controlled variable-speed drives are now replacing the less reliable solutions employed in older motor control generation. These so called ‘classic’ solutions such as universal motors or single phase induction motors used up to now present several limitations in terms of efficiency, safety and reliability. Depending on the end application and its functional requirements, either 3 phase induction motors (asynchronous motors) or permanent magnet synchronous motors will provide reliable operation with excellent dynamic control. With efficiencies up to 85% at high speed and 70% at low speed, these inverter drives based solutions can provide significant energy savings over standard PMDC. The key challenges are now to offer advanced algorithms to increase the ratio performances versus costs of the complete solution. Finally the new software techniques & new MCUs solutions are offering flexible solutions, easy to up-grade and easy to integrate.
Renesas Reference Platforms to address new Challenges
To address the increase of energy efficiency, Renesas is offering ‘Off the shelf’ solutions featuring sensorless Field Oriented Control algorithms. Each of the Motor Control Platforms is delivered with: • Boards schematics (MCU & power stage) • Bill Of Material, boards layout & Gerber files
• Software project source code running on HEW1)
• Specific PC GUI for serial user interface to drive the platform
• User’s Manual & calibration manual
Renesas approach is to offer very flexible Reference
Platforms (e.g. MCRPs2)), where any engineers may
evaluate the performance of the algorithms, add his own source code, adapt his own motor and optimise the complete system. As an example, the GUI PC interface below is used to calibrate any PSM motor (e.g. Permanent Magnet AC Synchronous, BLAC): Thanks to such PC interface, it becomes easy to adapt any specific or custom motors developed for a specific applications where the number of poles, the intrinsic rotor and stator parameters, etc.
1) High-performance Embedded Workshop: Renesas GUI to develop/debug/simulate any software. 2) Motor Control Reference Platforms
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1) High-performance Embedded Workshop: Renesas GUI to develop/debug/simulate any software. 2) Motor Control Reference Platforms
Renesas developed four main platforms in Europe to control the four types of motor presented above: PMDC, BLDC, PSM and Cast Motor. To adapt such platform to custom motors, Renesas is offering motor tuning & calibration services to speed- up any evaluation of the software algorithm & MCU capabilities. Please find below the Renesas Reference Designs overview & positioning
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PMDC Reference Platform: MCRP04
The Motor Control Reference Platform (MCRP04) integrates simple and low-cost electronics to efficiently drive any universal DC motors up to a power of 350 W. The method employed for driving the motor is a phase angle drive system running on the highly integrated R8C/13 microcontrollers. The platform is able to drive any high-voltage PMDC motors thanks to an isolated user interface. The user is able to adjust the motor speed by using an encoder and real time information is displayed on a simple LCD. Any tachometer can also be connected to enable speed feedback. A specific demonstration is available to simulate a washing machine program. It includes features such as a control relay for the door lock, drain pump and heater.
The user interface is used to control the platform and select a specific ‘Appliance mode’ to simulate a simple appliance including several steps activating actuators, reading temperature, etc.
The phase angle control technique is used to adjust the voltage applied to the load in order to achieve the desired speed.
On the picture below the platform is Voltage:
230...240 VAC motor up to 17,500 RPM for a maximum
current of 1.6 A and a power up to 350 W. Conclusion
Motor Type Universal DC Motor
Control Method Triac controlled
Waveform Type Trapezoidal (120°)
Rotor Position
Detection Tachometer
CPU Used R8C/13 , R8C/26
Resources Used 10% CPU, 4KB flash, 400 B RAM
Key Applications Low-end washer, Mixer, Air extractor, small appliances, Fan, etc. 220/110 VAC Main Supply Universal Motor Speed Sensor User Interface Board 220/110 VAC Input, 55 VAC Output 50/60 Hz transformer Power Stage Board CPU Board (R8Cx) I/O Simulation RS232 Serial Interface
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blDC Reference Platform: MCRP03
The MCRP03 is based on R8C microcontroller. It is design to offer low cost solutions to drive any Brushless DC motors with or without sensors. The driving technique use is the 120-degree block commutation.
The serial U/I is used to select the rotation-speed command. The MCU outputs the pattern accordingly to the state of hall-sensors signal. The PWM duty cycle is calculated by comparing the current speed of rotation with the reference rotation speed via a PI algorithm PWM signals are controlling only the high side IGBTs.
The PWM duty cycle is clamped to limit the motor current to its rated value. The switching of the output pattern is made every edge of the hall-sensors signal (6 times every electrical time period). Conclusion
Motor Type High & low voltage BLDC
Control
Method Block commutation (6 steps)
Waveform
type Trapezoidal (120°)
Rotor Position
Detection Sensorless (BEMF) or Hall sensors
CPU Used R8C/13 – R8C/25
Resources
Used 20% CPU, 4 KB flash, 400 B RAM
Switching
Frequency From 3...20 KHz
Key Applications
Water pumps (dishwasher), Air extractor, Washer, industrial drives, compressors, fan, Robotics, fork lift, door control, air conditioning, Central Heating Pump, etc.
24 Volt DC Power Supply
BLDC Motor HALL Sensors
User Interface Board Sensor/ Sensorless Board CPU Board Interface Board Power Stage Board
BEMF – Detection Lines
Serial Interface (RS232)
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PSM (PMaC) Reference Platform: MCRP05
This MCRP05 based on SH7125 or SH7085 MCUs controls any sensorless 3-phase Brushless Sinusoidal Synchronous motor inverter by using advanced Field Oriented Control algorithm (FOC). The motor used is a Brushless motor PSM also called Permanent Magnet motor (PMAC) or BLAC. The system is in closed loop as the current detection is done via a single shunt (three shunts is optional) which offers a very low cost solution and avoid any expensive encoder or current sensor.
The main focus applications are compressors, air conditioning, fans, industrial drives, washer, etc. The platform is flexible enough to develop any application using Brushless motors.
The MCRP05 is mainly divided into three parts: a CPU board, a Power stage & a low voltage demo system PSM motor. The user interface is a PC based GUI presented above.
Sensorless vector control algorithm using shunt current detection
Please, find below the FOC sensorless algorithm block diagram. The only different between the three shunts and the single shunt configurations is in the ‘Current Detection’ block, the rest of the algorithm remains the same. W [Speed Set] 0 [Id Set] + + + Id PI Iq PI Vq Vd Iq Id Vq Vu Vw Iu Iv Iw V´ V³ I´ I³
d, q --> ³, ´ ³, ´ --> U, V, W MODULATION inverterIPM Single shunt (3 shunts optional) Current detection U, V, W --> ³, ´ ³, ´ --> d, q Flux phase estimation Z[-1] Z[-1] Z[-1] Z[-1] 0 [Phase] Speed Estimation Z[-1] W [Estimated Speed] Speed PI
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Finally the key benefits of the MCRP05 are that the software is fully configurable to drive any low & high voltage PSM motors. The ‘customise-h’ file in
the project source code is a very useful and flexible file used to adapt the software without entering into the code itself.
#define SINGLESHUNT
Select one shunt or three shunts for current detection //#define THREESHUNTS
#define PWM_FREQ_CUSTOM 20000 PWM frequency modulation: between 3 KHz and 20 KHz
#define POSCURR Selects sign of the current read through the shunt and the related amplifier stage #define EEPROM_USED Enable the use of the external E²PROM
#define DISPLAY_USED Enable display usage
#define MCRP05_SCI0_CONNECTION Enable SCIO for external connection
#define SAMPLE_FREQ_CUSTOM 10000 Control loop time in Hz between 2500 Hz up to 10 KHz #define STARTUP_RAMPTIME_CUSTOM 800 Startup ramp time in ms
#define RPM_MIN_CUSTOM 600 #define RPM_MAX_CUSTOM 4500 #define R_ACC_CUSTOM 1000 #define C_POLI_CUSTOM 2 #define ID_NOM_CUSTOM 0 #define IQ_NOM_CUSTOM 30 #define R_STA_CUSTOM 7 #define KP_CUR_CUSTOM 150 #define KI_CUR_CUSTOM 100 #define KP_VEL_CUSTOM 30 #define KI_VEL_CUSTOM 20 min speed in RPM max speed in RPM acceleration ramp in RPM/sec polar pairs number flux current
max torque current in Arms/10 stator phase resistance in Ω/10 K prop. current control K integ. current control K prop. speed control K integ. speed control #define DEADTIM_CUSTOM 2.0 Dead-time value in μs @40 MHz #define RSHUNT_CUSTOM 100.0 #define RSGAIN_CUSTOM 5000.0 #define AVCC_CUSTOM 5000.0 Shunt value in mΩ Circuit gain x1000 A/D Range in mV #define RVBUS1_CUSTOM 400000.0
#define RVBUS2_CUSTOM 4700.0 Split resistor 1 in ΩSplit resistor 2 in Ω #define VIGBTV_CUSTOM 800.0
#define VDIODOV_CUSTOM 1400.0 VFree-wheel diode forward voltage in mVCESAT of the IGBT in mV #define FIRST_FLUX_LOWPASS_TIME_CUSTOM 10
#define DERIVATIVE_TIME_CUSTOM 1 #define LAST_FLUX_LOWPASS_TIME_CUSTOM 10
Flux phase estimation is made through following steps: 1) first low pass filter, 2) derivative, 3) last low pass filter #define FIRST_SPEED_LOWPASS_TIME_CUSTOM 5
#define SECOND_SPEED_LOWPASS_TIME_CUSTOM 4
#define THIRD_SPEED_LOWPASS_TIME_CUSTOM 3 Filters parameters
Conclusion
Motor Type High & low voltage PSM (e.g. Brushless AC) Control Method Field Oriented Control
Waveform Type Sinusoidal (180°)
Rotor Position Detection Sensorless (option to connect hall sensors or encoder) Motor Current Measurement Single shunt (option to use three shunts)
CPU Used SH7125 or SH7085
Resources Used 50% CPU, 8 KB flash, 1 KB RAM Switching Frequency From 3...20 KHz
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There are mainly two ways to drive 3-phase cast motors:
V/f Control Field Oriented Control (FOC) Simple to implement
(HW & SW) More difficult to implement Simple motor tuning
procedure Motor tuning required Speed control with speed
sensor is possible -
Speed control with speed sensor is possible
Sensorless speed control is possible
Separated Torque/Flux
control is not possible Separated Torque/Flux control is possible
Renesas chose the FOC approach because of the following benefits:
• Better dynamic behavior, if load variations are significant
• Much higher efficiency (due to flux control) • Much higher speed reachable
The performances of the sensorless systems are very good:
• Full starting torque
• Slip compensation (±3% over the full torque range of speed accuracy)
• Wide speed range (from 6 Hz till over 600 Hz) • High dynamic performances
• Current limits with speed reduction if maximum values are exceeded
• Less than 50% of CPU time is required for the SH7125
• Easy to customize to obtain the right compromise between required resources and obtained performances
Finally, the software parameters linked to the motor and the application are fully customisable, please find below the list of parameters that can
Cast Motor (aC asynchronous) Reference Platform: MCRP04
Renesas developed a fully vector controlled sensorless platform to drive any low and high voltages 3-phase cast motors. The MCRP06 is based on two boards: the CPU board is based on the 32-bit RISC SH7125 and the power board is featuring high voltage IPM (Integrated Power Module) and three shunts for the current detection. The Reference design is fully customisable: e.g. any serial communication, any encoder or hall sensor can be used.
Finally, the MCRP06 is also offered with the SH7286 MCU board featuring USB and CAN connections. The key benefits of a cast motor over PMDC motor are the following ones:
• Less acoustic noise
• The motor itself is much cheaper • No brushes, so more reliability • Long lifetime
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be easily adjusted via the User Interface. The board schematics, the layout and the software are fully available on the Renesas website.
Conclusion
Motor Type High & low voltage, Cast Motor (e.g. AC Asynchronous motors) Control Method Field Oriented Control Waveform Type Sinusoidal (180°) Rotor Position
Detection Sensorless (option to connect hall sensors or encoder) Motor Vurrent
Measurement Three shunts CPU Used SH7125 or SH7286 Resources Used 20% CPU, 8KB flash, 1KB RAM Switching
Frequency From 3KHz to 20KHz
Key Applications
Water pumps (dishwasher), Air extractor, Washer, industrial drives, compressors, fan, Robotics, fork lift, door control, air conditioning, etc.
Microcontrollers Roadmap for Motor Control
The low-end 16-bit MCU dedicated for Motor Control is based on the R8C Family perfectly designed to drive any PMDC motors and BLDC motor sensorless. On the other end, the SH Family is the high-end 32-bit RISC MCU specifically developed to control any PSM and Cast Motors using advanced vector controlled sensorless algorithms. Please find below the MCU overview for each motor type including the control methods.
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The common MCU features are the following: • High performance 16/32-bit CISC and RISC
Engine provides processing power for real time control
• Optional Floating Point Unit (FPU) and DSP capable CPU cores.
• Embedded Memory: max 1 MB flash, max. 40 KB RAM
• Integrated Multifunctional Timer Units targeted for Motor Control Applications
• Automatic Dead-time insertion & compensation. • Up to 12-bit High Speed Multi Channel A/D and
D/A Converters
• On-Chip Peripherals allow ease of interface to peripheral memory, LSI & host PC • Low Power Consumption modes for energy
saving applications
• On Chip Debug Modes facilitate ease of development and quick turnaround • Self-test CPU software routines to address
IEC60730-1 safety
Renesas MCU’s offer the right balance between performance and cost to meet the challenges imposed on motor control for a multitude of applications.
Motor Control applications
The current applications already mentioned above are now moving from single phase motor or PMDC motor to three-phase motor technologies. The key reasons are the gain of efficiency, safety and reliability. Please find below some example for each Renesas references designs:
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Conclusion
Renesas is offering state of the art software and reference designs to drive any advanced motors. Please find below the summary of the key differentiators:
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