KR20030091130A - encoder system for srm driving - Google Patents

Abstract

PURPOSE: An encoder device for driving an SRM(Switched Reluctance Motor) is provided to perform an on/off switching operation at a correct position by using a digital logic circuit including a decoder and a counter. CONSTITUTION: An encoder device for driving an SRM includes a disc, a pattern, the first photo coupler, and the second photo coupler. The disc is coupled to a rotary shaft. The pattern has the same period as the width of a position angle corresponding to a phase of an SRM driving inverter. A circular shape of the pattern is formed on the disc. The color sense becomes bright to a center of the pattern within one period. The color sense becomes dark to both sides of the pattern within one period. The first photo coupler is used for outputting the voltage proportional to the light reflected on the pattern. The second photo coupler is located at the predetermined position apart from the first photo coupler in order to output the voltage proportional to the light reflected on the pattern. The first and the second photo couplers are used for outputting two chopping waves having phase differences.

Description

Encoder device for SM drive {encoder system for srm driving}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device of a switched reluctance motor, and more particularly, to an SRM drive encoder device capable of performing ON / OFF switching at an accurate position and enabling stable operation in a wide range of speed ranges. It is about.

Since switched reluctance motors (SRMs) are derived from phenomenological methods, their origins are difficult to trace clearly, but they are based on the magnetic phenomena discovered by Ampere. Based on Ampere's theory in France in 1820, when current flows to the iron core solenoid, it acts like a permanent magnet in magnetic aspect. When the magnitude of the excitation current is properly adjusted, the same force generated in the permanent magnet is applied to the iron core solenoid. I started for the first time.

SRM is an electric device with simple electromagnetic structure, high efficiency, high torque / inertia ratio, variable speed operation in a wide range, etc., and is expanding its application area to home appliances, electric vehicles, aircraft, and industrial fields. And development is underway.

The driving principle of the SRM is that the rotational force is generated as the rotor is forced in a direction in which the magnetic resistance of the excited magnetic circuit is minimized. This phenomenon implies a physical meaning of minimizing the energy of the system by converting the energy stored in the system into mechanical energy. Devices using this principle include simple actuators, lifting magnets, linear solenoids, relays, step switches, and the like.

In order to maximize the reluctance torque, SRM has both the rotor and the stator structure of salient pole type, and the winding is wound around the stator only, so that the excitation power is intermittently and sequentially applied to each winding line. Let's do it.

The stator winding wire of the SRM requires information on the rotor position angle due to the characteristics of the torque generating mechanism that should be excited in synchronization with the rotor position. Rotor position angle detection generally uses an encoder or resolver, but the higher the resolution of such a mechanical external position sensor, the higher the unit cost. Therefore, in order to reduce the burden on the installation cost, the research on the sensorless driving to use a low-cost encoder, or to completely remove it has been actively conducted. This conventional technique uses a microprocessor to turn on / off the switches of each phase of an inverter driving SRM. However, in the SRM control method by the microprocessor, the degree of ON / OFF of the phase switch is limited by not only the resolution of the encoder but also the sampling cycle of the microprocessor. In this case, the higher the driving speed of the motor, the lower the accuracy of the phase switch ON / OFF angle by the microprocessor, which causes a problem that the normal operation state becomes unstable.

SRM is a motor that uses reluctance torque. In order to make the best use of it, the stator and the rotor are usually of salient structure, and the winding is wound around the stator only. At this time, the torque is generated in the direction of minimizing the reluctance of the magnetic circuit, and the magnitude of the generated torque is the current i flowing in the phase winding as shown in the following equation (1). Inductance for the square of and the rotor position angle θLProportional to the rate of change.

Therefore, the rate of change of the inductance should be maximized and the torque generation section should be utilized to the maximum by establishing and extinguishing the current corresponding to the load at the ON / OFF time of each phase switch. When voltage is applied to the stator winding of SRM, the equivalent voltage equation is given by the following equation (2).

only, : Mechanical angular velocity of the rotor [rad / s]

1 shows phase current waveforms A, B, and C according to phase inductance and ON / OFF angle change of the phase switch. In Fig. 1, θ min and θ max represent the rotor angles when the poles of the stator and the rotor start to overlap each other and coincide completely. Figure 1 (a) shows the switch OFF angle ( ) And keep the ON angle ( , , ), And the ON angle changes, the magnitude of the current established at the start of the torque generation section is different, and this value is almost the ON angle (ignoring the winding resistance of the motor). , , Is proportional to). In addition, the phase current waveforms A and C of the three waveforms A, B, and C have a positive or negative change rate of the current in the torque generation section, so that the generated torque is not constant and the torque pulsation is severe. However, the phase current waveform of B having a constant current in the torque generation section generates smooth torque when the inductance change rate is constant, and becomes a reference current for efficiently operating the motor due to less torque pulsation.

Figure 1 (b) shows the switch ON angle ( ) And the OFF angle ( , , ), The OFF angle ( , , ) Is closer to the maximum inductance point, which increases the utilization of the torque generating area, which is beneficial to the generation of positive torque, but if it is too large, it may be affected by the negative torque, causing torque pulsation and decreasing the mechanical output. Therefore, the switch ON angle should be determined so that the shape of the phase current becomes a smooth current regardless of the load torque and the operating speed, and the OFF angle should be adjusted so that no negative torque is generated so that the reluctance torque can be effectively used, and a small pulsation torque can be obtained. have.

A general configuration of a conventional SRM controller, which is widely used thus far, is briefly shown in FIG.

2, the controller 10, the inverter 20 using the IGBT module, the current and position sensor 40, the electric motor 30 and the like. The controller 10 is composed of a PWM generator 5 for controlling the phase current i, a speed controller 3, a speed calculator 9 by an output signal of the encoder 40, and the like. The speed controller 3 controls the difference 1 between the reference speed W * and the actual speed W to make the reference torque T *. Based on this reference torque T * and the detected rotor position angle θ, a reference current i * capable of generating a desired torque is obtained from the table 7. In addition, each current controller compares the reference current i * with the phase current i obtained through the current sensor so that the actual current follows the reference current i *.

In such a general driving system, since the SRM needs to be switched according to the rotor position angle, position information of the rotor is essential. In general, the rotor position angle is usually detected by installing a resolver or encoder on the motor shaft, and in particular, using an incremental encoder in consideration of the unit cost. The incremental encoder obtains the output pulse number according to the position as a digital value by an up or down-counter, and uses the microprocessor to control the signals of each phase.

However, the phase switch ON / OFF control method is highly dependent on the sampling cycle of the microprocessor. In particular, the higher the higher the speed, the lower the accuracy, which may lead to unstable operation of the SRM. There is a problem. Therefore, such a controller is generally implemented as a high-speed DSP to significantly reduce the sampling period, but there is a limit to the maximum speed for stable operation. In addition, there is a problem in that the use of a high-speed DSP, the price of the controller becomes expensive, which acts as a factor to inhibit the spread of SRM.

Accordingly, an object of the present invention is to provide a low-cost SRM driving optical encoder device suitable for stable driving of SRM in order to solve the above problems.

1 is a phase current waveform diagram according to changes in ON and OFF angles of a switching device.

2 is a block diagram of an SRM controller according to the prior art.

3 is a change in the switching angle according to the speed of the SRM.

4 is a pattern configuration diagram of an SRM driving encoder according to the present invention.

5 is an output waveform of the encoder for driving the SRM according to the present invention.

6 is an embodiment of an SRM controller according to the present invention;

7 is a schematic diagram of the structure and inductance profile of the SRM used in the verification of the present invention and a drive inverter circuit.

8 is a block diagram and operating waveforms of a current controller according to the present invention;

9 is a gate signal of each phase at the forward / reverse rotation of the SRM by the SRM drive encoder according to the present invention.

10 is a gate signal and a phase current waveform of the switching element when the SRM is 2500rpm.

Figure 11 shows the gate signal and phase current waveform of the switching element when the SRM is 2500rpm.

Figure 12 is a comparison of the phase current waveform in the prior art and the present invention when the SRM is 3600rpm.

<Description of the symbols for the main parts of the drawings>

10 controller 20 PWM inverter

30: electric motor 50: 80196KB

55: current controller 60: classic inverter

65, 69: decoder 67: counter

73, 75: analog switch 77: AND gate array

In order to achieve the above object, an encoder device for driving an SRM according to the present invention comprises: a disc configured to rotate in engagement with a rotating shaft of an SRM; In order to generate continuous torque when driving SRM, one phase of SRM drive inverter has a period equal to the width of the position angle to be in charge, and is formed in a circular shape on the disc, and the color becomes brighter toward the center within one cycle. A pattern configured to darken the color at the same ratio toward the side; A first photocoupler for irradiating light onto the pattern and receiving light reflected by the pattern and outputting a voltage proportional to the amount of received light; According to the inductance profile of the SRM to be driven, the SRM is spaced apart from the first photocoupler by an appropriate phase difference so that the SRM can generate a signal having the same shape as the forward rotation even in reverse rotation. A second photocoupler configured to receive a return light and output a voltage proportional to the amount of received light; and when the circular pattern is rotated in a state where power is applied to the first photocoupler and the second photocoupler, The first photocoupler and the second photocoupler are characterized in that to output two triangle waves having a phase difference.

A D / A converter for outputting an analog voltage proportional to an input digital value; And a comparator for comparing the triangular wave output signal of each photocoupler and the output of the D / A converter, wherein the D / A converter and the comparator convert the triangular wave output signal of the photocoupler to the gate signal of the SRM driving inverter. It is characterized by converting into a square wave suitable for generation.

Hereinafter, an SRM driving encoder apparatus according to the present invention will be described in detail with reference to the accompanying equations and drawings.

If the microprocessor is used to control the phase switch of the SRM, the control accuracy is determined by the resolution of the encoder. ) And the change in rotor position angle during the sampling period ( Is determined by That is, the mechanical position angle resolution in encoders with pulses per revolution Np is independent of the speed of the motor and the value is given by the following equation (3).

Also, the change in rotor position angle θ during the sampling period ( ) Depends on the speed of the motor and the value is as shown in the following equation (4).

Ts: Sampling period of the microprocessor [ s ]

Variation of ON and OFF angles in the phase switch control method using a microprocessor ( ) Is determined by the resolution of the encoder and the sampling period of the microprocessor, and the value is given from Equation (3) and (4) as shown in Equation (5).

The magnitudes of the ON and OFF angular fluctuations given by Equation (5) are shown in FIG. 3 according to the motor speed.

3, as the speed increases, the error due to sampling increases with a slope of 6Ts. In addition, if the resolution of the encoder and the position angle variation of the microprocessor do not appear as integer multiples, the lower harmonic components appear in the switching angle control. As a result, the same low harmonic components appear in the torque of the SRM, which adversely affects stabilization operation.

In general, when the speed of the motor is low, the variation of the position angle due to sampling is caused by the angular resolution of the encoder. ) Smaller than the variation in the ON / OFF angle is governed by the variations in the position of each sample, and the degree are subjected to controlled by the resolution of the encoder. However, the higher the speed of the motor, the more the encoder resolution remains unchanged, but the positional angle fluctuation by sampling becomes large.In this case, the variation of ON / OFF angle is subject to the positional angle fluctuation by sampling, and the degree is It is governed by the resolution of. Therefore, high-speed sampling is required to control the ON / OFF angle with a resolution similar to that of an encoder. A high-performance microprocessor is essential for this purpose. In order to control a high-precision phase switch without the help of such a high speed microprocessor, a special control method is required.

Therefore, in the present invention, in order to precisely control the on / off of the phase switch of the SRM drive inverter by using a simple encoder, the SRM drive encoder pattern of FIG. 4 has been developed.

Referring to FIG. 4, unlike the conventional digital optical encoder, the color of the disc of the encoder is changed linearly. The circular pattern is repeated at regular intervals, and in one cycle, the color becomes brighter toward the center, and the color darkens toward both sides. Therefore, as the encoder rotates, the amount of reflected light increases or decreases linearly, and thus the output of the light receiving element of the encoder becomes a triangular wave.

The period δ of the output pulse of the encoder having the pattern as shown in Fig. 4 (a) is determined by the following equation (6).

Pr: Number of poles of the rotor

When the cycle of the output pulse of the encoder is determined by the above equation (6), the cycle of the output pulse of the encoder for 8 / 6-pole SRM drive should be 60 °, so as shown in the pattern shown in Fig. 4 (a), It should consist of two repetitive patterns.

The period (δ) of the output pulse of the encoder having the pattern as shown in Fig. 4 (b) is determined by the following equation (7).

Ps: pole number of stator, Pr: pole number of rotor

When the period of the output pulse of the encoder is determined by the above equation (7), the period of the output pulse of the 8 / 6-pole SRM driving encoder should be 15 °, and thus, 24 as shown in the pattern shown in Fig. 4 (b). It should consist of two repetitive patterns.

The pulse width δ shown in Equation (7) may be used as the width of the position angle to which one phase of the SRM drive inverter is responsible for generating continuous torque in the SRM.

If the output period of the encoder is determined by the above equation (6), the rotor position angle for phase switching can be obtained completely, so that the position of the rotor can be grasped during startup, but the output of the encoder is made linear. The disadvantage is that it is very difficult. Therefore, very large difficulties are encountered in forming the same phase current waveform.

If the output period of the encoder is determined by Equation (7), the phase switch of the same type can be controlled by a simple circuit even if the output of the encoder is nonlinear, but the rotor position angle for phase switching is There is a drawback that the position of the rotor can not be grasped even at the start because it cannot be obtained completely. In this example, the output period of the encoder was determined by the above equation (7).

Next, the encoder according to the present invention as shown in FIG. 4 requires a photocoupler for forward rotation and reverse rotation. In the encoder, two photocouplers are installed with a phase difference by the machine angle γ, and each photocoupler is used as a part for forward rotation and a part for reverse rotation. The phase difference γ of the two phases of the encoder is used as a phase difference for forming a phase switch of the same type in the forward and reverse operation of the SRM, which is determined by the inductance profile of the SRM.

As described above, in order to configure the encoder according to the present invention, the inductance profile of the SRM to be controlled, the number of poles of the stator, and the number of poles of the rotor must be known in advance, and the inductance profile of the two photocouplers of the encoder Phase difference ) Should be determined appropriately, and the pulse width should be determined.

Figure 5 shows the output waveform of the encoder according to the present invention. Referring to Fig. 5, the inductance profile LA for one phase (phase A) of 8 / 6-pole SRM, the photocoupler output signals POTO_FW, POTO_BW of the encoder, the position angle command value Vref, and the FW and BW signals And the gate signals Phase_A_FW and Phase_A_BW at this time. As shown in FIG. 5, the photocoupler output signal of the encoder having the pattern as shown in FIG. 4 is in the form of a triangular wave. In Fig. 5, β represents the period of the inductance profile of the SRM, and its value is expressed by the following equation (8).

In the Phase_A_FW waveform of FIG. 5, the pulse width Φ is expressed by the following equation (9).

The Vref is a means for processing the triangular wave output Vp of the photocoupler into a pulse wave, which is a waveform of the gate signals Phase_A_FW and Phase_A_BW of the inverter, and using one D / A converter regardless of the forward and reverse rotation of the motor. It just happens. In FIG. 5, the FW and BW signals are signals after the output signals POTO_FW and POTO_BW of the photocoupler and the position angle command value Vref pass through the comparator. When the encoder device according to the present invention is actually used for driving the SRM, a comparator for generating the FW and BW signals of FIG. 5 by comparing the output signal of the photocoupler with the position angle command value as described above is required. That is, a first comparator for comparing the POTO_FW signal and Vref and a second comparator for comparing the POTO_BW signal and Vref are required. Such a D / A converter and the comparator may be mounted together with a photocoupler on a circuit board inside the encoder, or may be configured as part of the controller when designing an SRM controller to be described later. In the following description, the FW signal and the BW signal will be treated as the final output signal of the encoder in order to prevent the description from being complicated.

The FW signal may be used to generate the gate signal of the phase switch in the forward rotation of the SRM, and the BW signal may be used to generate the gate signal of the phase switch in the reverse rotation. The direction of rotation can be detected by applying the FW signal and the BW signal to the encoder's forward and reverse determination circuits.

Next, the SRM controller using the SRM drive encoder according to the present invention for detecting the rotational speed and position of the SRM will be described. An embodiment of an SRM controller is shown in block diagram in FIG. And through the experiments will be described the performance of the encoder and the SRM controller using the same according to the present invention.

The SRM used in the experiment is a pole of the stator and the rotor of 8/6, 400W, 3000rpm, 160V equipment has a structure as shown in Figure 7 (a), to drive it, the conventional classic inverter as shown in Figure 7 (c) Was used. The inductance profile of this motor is shown in Fig. 7 (b), which changes the rotor by 1 ° and sets the current limit to 7 [A] and applies a voltage pulse until the limit is reached and then the current waveform at that time. After measuring with an oscilloscope, the inductance was calculated from the measured voltage and current data in consideration of the winding resistance of the motor. Therefore, the inductance profile obtained is a relatively accurate value that can represent the dynamic operation characteristics of the SRM.

Next, the phase difference between the value of δ, which is the pulse width of the encoder to be used for the rotation speed and the position detection of the SRM having the characteristics as shown in FIGS. 7 (a) and 7 (b),

Is determined by referring to the inductance profile of Equation (7) and FIG. 7 (b), and configured the encoder according to the determined value. Since it is an 8 / 6-pole SRM, substituting in equation (6) above is δ = Becomes Thus, δ = The encoder pattern was configured. And Has been appropriately set up based on a number of experiences.

Next, the configuration of the SRM controller will be described in detail with reference to FIG.

Referring to Figure 6 briefly, there is a large controller on the left side and the inverter 60 on the right side again, the controller is a microcontroller 80196KB (50), and the peripheral circuits 71, ABS, for accepting an external input from the 80196KB (50) COMP), a current controller 55 for controlling the inverter 60 using an output signal of 80196KB (50), a decoder 65,69, an analog switch 73, 75, a counter 67, And a digital logic circuit using the AND gate array 77.

The FW and BW signals are inputted to the first decoder 65, the clock generation circuit 71, and the HSI0 and HSI1 terminals of the 80196KB 50, and the D0 output and the D2 output of the first decoder 65 are connected to the first analog switch ( Connected to the input of 73, the output of the first analog switch 73 is input to the clock terminal of the counter 67; On the other hand, the FW and BW signals are connected to two input sides of the second analog switch 75, and the output of the second analog switch 75 is connected to one input terminal of each AND gate of the AND gate array 77. The first analog switch 73 selects one of the D0 output and the D2 output of the first decoder 65 and outputs it to the counter 67 under the control of the P1.3 terminal output signal of 80196KB 50. . The second analog switch 75 is controlled by the P1.3 terminal output signal of 80196KB 50 and selects one of the FW signal and the BW signal and outputs the signal to the AND gate array 77. The output signal of the P1.3 terminal of the 80196KB 50 is the selection signal Dir for selecting the forward / reverse direction.

The clock generation circuit 71 is a logic circuit configured to measure the speed of the motor by the M / T technique, which is a speed calculation method using an encoder in 80196KB (50). Therefore, the FW signal and the BW signal, which are output signals of the encoder, are input to the clock generation circuit 71 and processed into a single clock signal CLK and an up-down signal UP / DOWN.

The output signal of the clock generation circuit 71 is input to the timer 2 (T2CLK, T2UPDN) at 80196KB (50), and configured to calculate the speed (Wr) of the motor by a software method (Wr estimation).

The 80196KB 50 receives the FW signal and the BW signal of the encoder through the HSI terminals HSI0 and HSI1 to detect the phase θ of the motor by an internal program θestimation. In this way, the phase is detected to determine the forward and reverse rotation of the motor.

The digital logic circuit including the first decoder 65, the analog switches 73 and 75, the counter 67, the AND gate array 77 and the second decoder 69 to be described later has been described. This will be described later.

Next, the outputs C0 and C1 of the counter 67 are input to the second decoder 69 of the next stage, and the outputs QA, QB, QC and QD of the second decoder 69 are AND gate arrays. The input terminal is input to one of two input terminals of each AND gate of (77). Therefore, the output of the second analog switch 75 and the output of the second decoder 69 are input to each AND gate of the AND gate array 77. The output of the AND gate array 77 is configured to control the switching elements of the inverter 60, that is, the phase switches QAU, QBU, QCU, QDU. 6 shows only a circuit for one phase (A phase) of the inverter 60. The circuits for the remaining three phases B, C, and D of the classic inverter 60 are similar to those for the A phase and thus are omitted. The detailed circuit of the classic inverter 60 is shown in Fig. 7 (c).

On the other hand, the output signal of the P1.0 to P1.2 terminal of the 80196KB 50 controls the counter 67, and the output of the second decoder 69 to the P0.4 to P0.7 terminal of the 80196KB 50 ( Q0 to Q3) are input.

The 80196KB 50 detects the outputs Q0 to Q3 of the AND gate array 77 through the P0.4 to P0.7 terminals to determine whether the switching sequence is correct when starting or operating the SRM. Check by). If a malfunction occurs, the switch state is changed through Port1 (P1.0 to P1.3).

Next, the PWM1 signal output from the PI controller in the 80196KB 50 is input to the low pass filter LPF, and the output of the low pass filter LPF is input to the current controller 55 of the next stage. The output of the current controller 55 is input to the AND gate together with the output Q0 of the AND gate array 77, and the output of the AND gate is configured to control the phase switch QAD of the classic inverter 60. have.

The current controller 55 is configured to make the initial position of the motor constant at the start of the motor, and a detailed configuration of the current controller 55 is shown in FIG.

When driving the motor by the method proposed in the present invention there is no information on the initial position angle of the motor. In order to solve this problem, in this embodiment, the initial position is made constant by flowing a rated current on an arbitrary phase before starting the SRM. The current controller is essential for flowing the initial starting current.

Referring to FIG. 8, the current controller 55 of FIG. 8 (a) is composed of a comparator 57 and a flip-flop 59, and is configured to control current in a peak current control method. In Fig. 8, the current command value Ia_Ref is an output signal of the low pass filter LPF as shown in Fig. 6, and the actual current Ia_Real is fed back from the emitter terminal side of the switching element QAD of the inverter 60. Current detected. Fig. 8B is an operating waveform of each part of the current controller 55. Figs.

When the set terminal of the flip-flop 59 is turned on for each switching cycle to turn on the switch, the real current Ia_Real increases, and the comparator 57 compares the current command value Ia_Ref with the real current Ia_Real to actually When the current Ia_Real becomes larger than the setpoint current Ia_Ref, the reset terminal of the flip-flop 59 is enabled to turn off the switch QAD shown in FIG. 6, thereby reducing the current flowing into the motor. Due to this current control method, the rapid response of the SRM controller has the same excellent characteristics as the delta modulation method, and the switching frequency can be made constant.

Next, looking at the lower left of Figure 6, + VC is connected to one side of the variable resistor, the other side of the variable resistor is connected to -VC, the variable resistor is an absolute value circuit (ABS) and a comparator (COMP) Becomes the input of. The output of the absolute value circuit ABS is input to the A / D converter terminal AD0 of 80196KB (50), and the output of the comparator COMP is input to the P1.4 terminal of 80196KB (50).

The variable resistor is a variable resistor for adjusting the speed of the motor. A user's speed command value (Wr *) is accepted as a digital value by using the A / D converter function of 80196KB (50). The A / D converter of 80196KB (50) is not accurate with 8 bits of resolution. Therefore, in the present embodiment, the absolute value circuit ABS and the comparator COMP are added for more precise speed control, and the output of the 8-bit A / D converter and the comparator COMP in the 80196KB 50 are software-configured. The output is ORed to improve the resolution to 9 bits.

Next, a digital logic circuit including the first decoder 65, the analog switches 73 and 75, the counter 67, the AND gate array 77, and the second decoder 69 will be described.

The digital logic circuit is configured in this embodiment in accordance with the output signal of the encoder for driving the SRM proposed in the present invention so that the response of the controller is made at high speed. In the present embodiment, the digital logic circuit is regarded as a part of the SRM controller. However, when the encoder pattern is determined according to the number of poles of the stator and the number of rotors of the SRM, the schematic configuration of the digital logic circuit is also determined. And digital logic circuits can be regarded as encoder devices. In this sense, the previous D / A converter and comparator can be regarded as encoder devices.

As described above, the phase switch on / off control method by the microprocessor is largely influenced by the sampling of the microprocessor, and the degree thereof is lowered at a high speed, and thus the steady state operation of the SRM becomes unstable. However, in the present invention, the output signal of the encoder is properly processed using a digital logic circuit, and then a method of controlling the phase switch of the inverter 60 is introduced to speed up the controller. In the present invention, since the microprocessor 50 merely controls the stationary range of the motor or checks whether the phase switch on / off signal is properly output from the digital logic circuit, the microprocessor 50 controls the gate signals Q0 to Q3 of the phase switch. Is not involved in the creation of). Since the gate signals Q0 to Q3 of the phase switch are automatically generated by the digital logic circuit, the controller reacts at high speed. Looking at Figure 9 to be described later will be able to confirm this fact.

Next, a 2 to 4 decoder was used as the first decoder 65. As the counter 67, a 2-bit counter was used, and as the second decoder 69, a 2 to 4 decoder was used. The reason for this configuration will be described with reference to FIG.

Fig. 9 shows FW and BW signals in which the inductance profile (LA, LB, LC, LD) of each phase of the experimental 8/6 SRM by the encoder proposed in this invention and the output of the photocoupler of the encoder are processed for forward / reverse rotation of the motor. And gate signals A, B, C, and D of each phase during forward and reverse rotation operation. 9, the gate signals A, B, C, and D of each phase switch are repeated every four counts of the FW and BW signals. Therefore, it can be seen that the forward signal of the SRM may be used as the ON signal of each phase switch every 4 counts based on the FW signal. In addition, it can be seen from FIG. 9 that the reverse rotation of the SRM may be used as the ON signal of each phase switch every 4 counts based on the BW signal. Therefore, in order to process the FW signal and the BW signal into the ON signal of each phase switch, a combination of a 4bit shift register or a ternary counter (2 bit counter) and a 2 to 4 decoder to make a sequential signal repeated in ABCD phase order is used. Simple solution. When using the 4-bit shift register, four control lines are required to set the initial value of the phase switch. However, when the combination of the ternary counter and the 2 to 4 decoder is used, the phase switch can be set using the two control lines. Therefore, in the present embodiment, as shown in Fig. 6, the FW signal and the BW signal are converted into phase switch gate signals A, B, C, and D using a 2 to 4 decoder 67 and a 2-bit counter 69. It was configured to process. However, it is also possible to configure using a 4-bit shift register without following this embodiment.

The first decoder 65 and the first analog switch 73 are configured to extract the clock signal of the counter 67 from the FW signal and the BW signal. The counter 67 counts in synchronization with the input clock signal and should output a signal having the same period as the input clock signal. Therefore, in the present embodiment, the first decoder 65 is used to extract the clock signal having the same period as the FW signal from the logical relationship between the FW signal and the BW signal. Since the motor should be synchronized with the FW signal when the motor rotates forward, the output signal of the D0 terminal of the first decoder 65 is input as the clock signal of the counter 67 by using the first analog switch 73. In reverse rotation, the output signal of the D2 terminal of the first decoder 65 is input as the clock signal of the counter 67 using the first analog switch 73 so as to be synchronized with the BW signal.

As described above, the first analog switch 73 is used to select the forward-only signal and the reverse-only signal as described above. However, it is also possible to configure to select using a relay, a data selector, or the like without following the present embodiment.

Next, in the second analog switch 75 and the AND gate array 77, the gate signal of the phase switch has the same pulse width as that of the FW and BW signals as shown in FIG. 9 and is synchronized with the FW and BW signals. It is a configuration to ensure that. That is, the output signal of the second decoder 69 is a sequential signal that can sequentially turn on / off the phase switch gate signal of the inverter, but it must be synchronized with the FW and BW signals based on the inductance profile to drive the SRM. Therefore, in order to achieve synchronization, the present embodiment is configured such that the output signal of the second decoder 69 is output to the inverter side only when the FW signal or the BW signal is high by using the AND gate 77. The second analog switch 75 is configured to select the synchronization signal of the output signal of the second decoder 69 among the FW signal and the BW signal.

Next, the operation of the SRM controller shown in FIG. 6 will be briefly described.

Once the rotor is positioned at the point where the C phase inductance of the SRM is maximum for starting, it can be placed in the area where the A phase inductance increases in the forward rotation, and the D phase inductance in the increase region in the reverse rotation. Therefore, the 80196KB 50 outputs a signal to the P1.0 and P1.1 terminals, and sets the QC terminal of the second decoder 69 to be turned on when the counter 67 is enabled to output the signal. The terminals A and B of the counter 67 are terminals for presetting the counter 67. When the counter 67 outputs '10', the QC terminal of the second decoder 69 is turned on. Therefore, setting the A and B terminals of the counter 67 to '10' will start counting from '10' when the counter 67 is enabled. Next, 80196KB 50 outputs a signal to the P1.2 terminal to enable the load terminal L of the counter 67. Then, the counter 67 outputs a binary number '10', the QC terminal of the second decoder 69 is turned on and coordinates with the current controller 55 to position the position of the motor rotor at the desired initial position.

When the rotor of the motor is placed in the initial position, the motor is started next. For the forward rotation, the first decoder 65 is controlled by controlling the first analog switch 73 with a P1.3 terminal output signal of 80196KB (50). After selecting the output signal of the D0 terminal as the clock input of the counter 67 (DIR terminal), the QA of the second decoder 69 is turned on by using the load terminal of the counter 67. For reverse rotation, the analog switch 73 is controlled by the P1.3 terminal output signal of 80196KB (50) to select the output signal of the D2 terminal of the first decoder 65 as the clock input of the counter 67, and then the second decoder. The QD of (69) may be turned on.

80196KB (50) checks the upper 4 bits (P0.4 ~ P0.7) of Port0 to verify that the switching sequence at startup and operation is correct. Check the upper 4 bits (P0.4 ~ P0.7) and if the switching sequence is not correct, set the A and B terminals of the counter 67 properly through Port0 (P1.0, P1.1), and set the counter (67). ) Is enabled to control the output of the second decoder 69 to a desired state to change the state of the phase switch of the inverter (60).

On the other hand, 80196KB (50) receives the FW, BW phase of the encoder to the HSI pin. 80196KB (50) detects the phases of the encoder's FW and BW to determine whether the motor is rotating forward or reverse by internal program (θestimation), and the speed is 80196KB (50) Timer2 (T2CLK, T2UPDN). It calculates by M / T method which is a speed calculation method by the existing encoder.

After the description of the SRM driving encoder device and the SRM controller proposed in the present invention, the results of the SRM driving experiment performed using the SRM driving encoder device and the SRM controller proposed in the present invention will be described with reference to the drawings.

When the SRM rotates clockwise in the forward direction and the counterclockwise rotates in the reverse direction, Fig. 10 (a) shows two linear photocouplers when the SRM rotates forward at 2500 [rpm]. The outputs 101 and 102 and the position angle displacement command values Vref and 103 and the output signal 104 of the FW are shown.

Fig. 10B shows the output 105 of the linear photocoupler, the position angle displacement command value 106, the FW signal 107 and the gate signal 108 on the A phase. Fig. 10C shows the FW signal 109 and the A-C phase gate signals 110 to 112. Figs. Fig. 10 (d) shows the gate signal of each phase.

As shown in FIG. 10, the encoder device according to the present invention can turn on and off a phase switch at a constant rotor position angle even at a high speed, and thus the phase current has almost the same shape. When the encoder device is used, a very stable speed and torque are achieved. It shows that control can be made. Accurate and stable phase switch on and off is very helpful for the system stability in steady state.

Next, Fig. 11 shows waveforms of experiment results when the SRM rotates forward at 2500 [rpm]. Fig. 11A shows the A and B phase signals 113 and 115 at the forward rotation and the phase current waveforms 114 and 116 at this time, and Fig. 11B shows each phase current. As shown in Fig. 11, it can be seen that the phase current has almost the same shape by turning the phase switch ON and OFF at a constant rotor position angle.

Next, FIG. 12 is an experimental result waveform for comparing phase switching stability in the proposed microprocessor method and the proposed method when the SRM is rotating forward at 3600 [rpm]. 12 (a) is a conventional switching method using a microprocessor, the degree of on / off angle control of the phase switch is reduced so that the phase current waveform cannot be uniform. As a result, there is a significant ripple in the torque. On the other hand, in Fig. 12 (b) which is a phase switching method by the proposed encoder device, the on and off angles are always controlled at a constant position, so that the phase current waveform is kept constant.

As described above, in the present invention, a low-cost encoder suitable for SRM driving is proposed, and an SRM driving process for outputting the output signal of the proposed encoder into a phase switch gate signal of an SRM driving inverter by a digital logic circuit using a decoder and a counter, etc. We proposed an encoder device. If the SRM controller is designed using the proposed SRM drive encoder device, the switch ON and OFF angle delays are always constant regardless of the operation speed of the SRM. Not only is this possible, there is an advantage that forward and reverse operations are also possible.

In addition, the SRM controller does not require a high-speed microprocessor, and since the low-cost encoder is used, there is an advantage that stabilization and low cost of the SRM drive system can be realized. Therefore, the possibility of practical use of SRM is further enhanced.

Claims (2)

A disc configured to rotate in engagement with a rotation axis of the SRM; In order to generate continuous torque when driving SRM, one phase of SRM drive inverter has a period equal to the width of the position angle to be in charge, and is formed in a circular shape on the disc, and the color becomes brighter toward the center within one cycle. A pattern configured to darken the color at the same ratio toward the side; A first photocoupler for irradiating light onto the pattern and receiving light reflected by the pattern and outputting a voltage proportional to the amount of received light; According to the inductance profile of the SRM to be driven, the SRM is spaced apart from the first photocoupler by an appropriate phase difference so that the SRM can generate a signal having the same shape as the forward rotation even in reverse rotation. And a second photo coupler configured to receive the returned light and output a voltage proportional to the amount of received light. And the first photo coupler and the second photo coupler output two triangular waves having a phase difference when the circular pattern rotates while power is supplied to the first photo coupler and the second photo coupler. The method of claim 1, A D / A converter for outputting an analog voltage proportional to an input digital value; And a comparator for comparing the triangular wave output signal of each photocoupler with the output of the D / A converter. And the D / A converter and the comparator convert the triangular wave output signal of the photocoupler into a square wave suitable for generating the gate signal of the SRM driving inverter.