1、PDF外文：http:/ A 英 文文献 原文 Development of a Novel Drive Topology for a Five Phase Stepper Motor T.S. Weerakoon and L. Samaranayake （ Dept. of Electrical and Electronic Engineering, Faculty of Engineering, University of Peradeniya, Sri Lanka） AbstractIn this paper, a novel drive topolo
2、gy for a five phase stepper motor is described in detail. Commercially off the shelf, low cost, standard stepper motor drive ICs are used to derive a novel drive topology for five phase stepper motors which enables closed loop speed and position control powered by inner current control loop. It is p
3、roved that the derived topology can be generalized to any stepper motor with higher odd number of phases. The designed driver consists of full step, half step, clockwise and counter clockwise drive modes with the speed control and current control. key wordsFive-phase stepper motor, the return
4、drive, speed control, multi-mode I. INTRODUCTION In most of the robotics and automation engineering designs various types of stepper motors are used to obtain the required motion profiles. Stepper motors are preferred, as they do not require frequent maintenance and due to their ability to operate i
5、n many harsh environments. Selection of the motors and their drive circuits depend on the required performance characteristics of the applications.The two phase and four phase stepper motors are the most common types available in the market. However, for applications requiring high precision, low no
6、ise and lower vibration, Five Phase Stepper Motors are used. Due to smaller step angle, five phase stepper motors offer higher resolution, lower vibration and higher accelerations and decelerations. Therefore it is essential to make sure that these motor characteristics can be obtained from the desi
7、gned drive topology. Because the five phase stepper motors are a rarely used type in the robotic applications and the construction is typically complicated, it is very difficult to find driver ICs, which are manufactured exclusive for them. As a result, the available Driver circuits for five phase s
8、tepper motors are very expensive. Using the available drive control ICs manufactured for common kinds of stepper motors such as 2 phased and 4 phased and using them in modeling new driver topology for other stepper motors would be a cost effective approach. The IC L297 integrates all the control cir
9、cuitry required to control bipolar and unipolar stepper motors. The L298N dual H bridge drive forms a complete microprocessor to stepper motor interface. Here, novel drive topology is investigated and developed for five phase stepper motors by adding a microprocessor and logical control system with
10、L297 and L298N. The complete topology is described in this paper. Section II explains the component characteristics. Section III is on the control logic circuit design phenomena. The interface design is given in Section IV with results in Section V. Finally the conclusions are presented in Section V
11、I. II. CHARACTERISTIC ANALYSIS OF MAIN COMPONENTS The IC L297 can be used with an H bridge driver IC for motor drive applications as shown in Fig.1.1. In this design H bridge function is achieved from the L298N or L293E. This may change depending on the power rating of the motor. The control signals
12、 to the L297 may be received from microcontroller or from external switches. A single IC can drive a 2 phase bipolar permanent magnet motor, a 4 phase unipolar permanent magnet motor or a 4 phase variable reluctance motor. Because very few electronic components are used, it has many advantages such
13、as lower cost, higher reliability and the ability to house in a comparatively smaller space. The L297 generates three modes of phase sequences, namely half step mode, full step mode and wave mode depending on the input signals it receives. H A L F / F U L L1 9C W / C C W1 7C L O C K1 8H O M E
14、3R E S E T2 0A4B6C7D9I N H 15I N H 28E N A B L E1 0S Y N C1C O N T R O L1 1O S C1 6V R E F1 5S E N S 11 4S E N S 21 3V C C1 2G N D2U 1L 2 9 7I N 15I N 27E N A6O U T 12O U T 23E N B1 1O U T 31 3O U T 41 4I N 31 0I N 41 2S E N S A1S E N S B1 5G N D8V S4V C C9L 2 9 8R V 11 kV C CR 11 0 kC 21 n FR 21 0
15、kR 31 0 kV C CD 11 N 9 1 4D 21 N 9 1 4D 31 N 9 1 4D 41 N 9 1 4D 51 N 9 1 4D 61 N 9 1 4D 71 N 9 1 4D 81 N 9 1 4 Fig. 2.1 Circuit diagram to drive a 2 phase bipolar or 4 phase unipolar stepper motor using L297 and L298N ICs A CURRENT CONTROL Small stepper motors generally need small DC sup
16、plies that control the winding currents and they are limited by the winding resistances. On the other hand, motors with the larger rated torque values have windings with smaller resistances.Therefore, they require a controlled current supply. The L297 provides load current control in the form of two
17、 Pulse Width Modulation (PWM) chopper circuits and each chopper circuit consists of a comparator, a flip-flop and an external sensing resistor. In this method, while the motor current is increasing, the control system applies the supply voltage to the motor. When the current is reached up to the thr
18、eshold, the control system tries to maintain the current at the desired value by changing the duty ratio of the voltage supply as shown in Fig.2.2. For each chopper circuit, the duty ratio (D) of the voltage supply to the motor is defined as: D = Ton / (Ton + Toff), where the Ton and Toff are switch
19、 on and off durations respectively of the H bridge. In the chopper circuit, the flip-flop is set by each pulse from the oscillator, enabling the output and allowing the load current to increase. As it increases the voltage across the sensing resistor increases and when this voltage reaches Vref the
20、flip-flop is reset, disabling the output until the next oscillator pulse arrives. In this method Vref determines the peak load current. The L298N is a monolithic circuit contains two H bridges. Inaddition, the emitter connectionsof the lower transistors arebrought out to external terminals allowing
21、the connection ofcurrent sensing resisters. QQS E TC L RSRV - r e fc o m p a r a t o rV - s e n s eF r o m O S C Fig. 2.2 Circuit containing the flip-flop, the oscillator and the comparator used for current controlling B. CURRENT CONTROL IN INHIBIT CHOPPER MODE Inhibit chopper cont
22、rol mode and phase line chopper controlmode are two of the most common types of current controltechniques available. In the latter case when the voltage acrossthe sensing resistor reaches to Vref, only the low side switch ismade off. Hence this method is not suitable and inhibit choppercontrol mode
23、has to be used. The required switching sequencesfor this can be taken directly from L297. Inhibit chopper mode can be selected by pulling down(grounded) the CONTROL input signal of L297. Then chopperacts on INH to control the current through the motor coils.Therefore the contribution of INH signal g
24、enerated from L297 isvery important to create ENABLE signal for L298N. In the casewhen the voltage across the sensing resister reaches to Vref, thechopper flip-flop is reset and INH is activated and is brought tolow. Then it turns off all four switches of the bridge. Thechopping frequency is determi
25、ned by the internal oscillator ofthe L297. After switching off all transistors, the diodes providea path to divert the winding current. The switches of the Hbridge are made on in the next oscillator cycle. III. LOGIC CIRCUIT DESIGNING In any mode of operations, wave patterns of A, B, C and Dphases of the L297 repeat after four clock cycles as shown inFig.3.1. Translation of the repetition of the phase waveform afterthe ten clock cycles is essential to derive the drive topology forthe five phase stepper motor.
