Microchip Technology Inc. Motor Types

Common Motor Control Elements Measure Calculate Control Rotation Position Temperature Pulse Width Modulation Power Drivers Timing Math Functions

Primary Motor Types DC Brush Motor DC Brushless Motor Stepper Motor AC Induction Switched Reluctance The four types of motors that we will discuss are the DC Brush Motor, the Stepper Motor, the DC Brushless Motor, and the Switched Reluctance Motor. For each motor we will discuss construction, operating principles, and important concepts related to control electronics that may utilize PICmicro devices. It will be evident that common principles are shared by each motor type. We will spend most of our time on the DC brush motor and the stepper motor, since the other two motors can easily be understood with reference to these.

DC Brush Motor Common Control Implementations PICmicro® MCU solutions Simple power stage control May use position feedback sensors for closed loop control PICmicro® MCU solutions 4Kw 28-pin to 32Kbyte 64-pin Ex. include PIC16F876 and PIC17C766 The two basic control methodologies for the SR are closed-loop and sensorless Closed-loop control is realized with the use of incremental encoders. Rotor position information is required for synchronized phase switching patterns. The sensorless control strategies eliminate the rotor position sensor. One technique applies short pulses to the non-excited stator coils. The difference in current at two different instances is obtained so that the stator inductance can be calculated. This is sometimes referred to as inductance signatures. The stator inductance is a function of the instantaneous rotor position. For the ACIM, BLDC and SR motor types the sensorless control approach seems to be gaining popularity. Being able to eliminate the rotor positioning feedback sensors is a plus and reduces system costs. The issue with this approach is that increased computational horsepower is typically required along with additional program memory and a fast ADC. Typical Customer PICmicro implementations from design wins information.

DC Brushless Motor Common Control Implementations Closed-loop control Sensor and sensorless control PICmicro® MCU solutions TC6XX Fan Controller Family 4Kw 28-pin to 16Kw 64-pin Ex. include: PIC16C73 and PIC18C658 The various types of motors listed here and on the next few slides are those which we should support. Each motor type has its own pros and cons for an application. Various control strategies exist for each of the motor types, each with its own pros and cons. The three basic control methodologies for the ACIM are open-loop, closed-loop and sensorless. These three control methodologies can be further divided into: V/F control (scalar control) Slip frequency control Vector control (Field orientated control) Sensorless vector control (Kalman observer) strategies are used to predict the rotor position based on the characteristics of the motor and the measured phase currents. The two basic control methodologies for the BLDC are closed-loop and sensorless. Closed loop control relates to the use of rotor feedback information provided by Hall sensors for motor commutation states. It is noted here that rotor positioning information can also be derived from incremental encoders as well. Sensorless control does not implement Hall sensors but rather rotor positioning information is derived for sensing back EMF on a non-energized motor winding.

Stepper Motor Common Control Implementations PICmicro® MCU solutions Open Loop Control Simple and inexpensive control PICmicro® MCU solutions 2Kw 8-pin to 16Kw 40-pin Ex. include: PIC12C509A and PIC18C452 The various types of motors listed here and on the next few slides are those which we should support. Each motor type has its own pros and cons for an application. Various control strategies exist for each of the motor types, each with its own pros and cons. The three basic control methodologies for the ACIM are open-loop, closed-loop and sensorless. These three control methodologies can be further divided into: V/F control (scalar control) Slip frequency control Vector control (Field orientated control) Sensorless vector control (Kalman observer) strategies are used to predict the rotor position based on the characteristics of the motor and the measured phase currents. The two basic control methodologies for the BLDC are closed-loop and sensorless. Closed loop control relates to the use of rotor feedback information provided by Hall sensors for motor commutation states. It is noted here that rotor positioning information can also be derived from incremental encoders as well. Sensorless control does not implement Hall sensors but rather rotor positioning information is derived for sensing back EMF on a non-energized motor winding.

AC Induction Motor Common Control Implementations Open-loop control Closed-loop sensor and sensorless control PICmicro® MCU solutions 4Kw and 8Kw, 28 and 40 pins Ex. include: PIC16C773, PIC16C774, PIC16F873, PIC16F874 The various types of motors listed here and on the next few slides are those which we should support. Each motor type has its own pros and cons for an application. Various control strategies exist for each of the motor types, each with its own pros and cons. The three basic control methodologies for the ACIM are open-loop, closed-loop and sensorless. These three control methodologies can be further divided into: V/F control (scalar control) Slip frequency control Vector control (Field orientated control) Sensorless vector control (Kalman observer) strategies are used to predict the rotor position based on the characteristics of the motor and the measured phase currents. The two basic control methodologies for the BLDC are closed-loop and sensorless. Closed loop control relates to the use of rotor feedback information provided by Hall sensors for motor commutation states. It is noted here that rotor positioning information can also be derived from incremental encoders as well. Sensorless control does not implement Hall sensors but rather rotor positioning information is derived for sensing back EMF on a non-energized motor winding.

Switched Reluctance (SR) Motor Common Control Implementations Closed-loop sensor and sensorless control PICmicro® MCU solutions 2Kw/4Kw 18/28 pins Ex. Include: PIC16C622, PIC16C73, PIC16F873 Trend moving to higher memory PIC18FXXX and dsPIC™ families The two basic control methodologies for the SR are closed-loop sensor and sensorless control. Closed-loop control is realized with the use of incremental encoders. Rotor position information is required for synchronized phase switching patterns. The sensorless control strategies eliminate the rotor position sensor. One technique applies short pulses to the non-excited stator coils. The difference in current at two different instances is obtained so that the stator inductance can be calculated. This is sometimes referred to as inductance signatures. The stator inductance is a function of the instantaneous rotor position. For the ACIM, BLDC and SR motor types the sensorless control approach seems to be gaining popularity. Being able to eliminate the rotor positioning feedback sensors is a plus and reduces system costs. The issue with this approach is that increased computational horsepower is typically required along with additional program memory and a fast ADC.