JPS61244300A - Driving method for stepping motor - Google Patents

Abstract

PURPOSE:To largely improve the heat resistant life of an exciting winding by stopping a motor in 1-phase excitation, thereby reducing the power consumption at the stopping time. CONSTITUTION:A signal for supporting a signal to be added to exciting windings to drive a stepping motor 14 is input from the output terminals P0, P1, P2, P3 of a CPU 22 to a stepping motor drive circuit 26. Since 1-phase excitation and 2-phase excitation are alternately repeated, when a pulse sequence for instructing a throttle valve stopping position is always set to become 1-phase excitation state, the current consumption at the stopping time becomes half as compared with that at 2-phase excitation. Accordingly, the generated heat is largely reduced.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a method for driving a stepping motor, and in particular to a stepping motor that reduces the self-temperature rise of the stepping motor when stopped, improves reliability, and extends the life of the stepping motor. The present invention relates to a driving method.

(Prior Art) A motor that rotates a sidewalk by a fixed angle by sequentially energizing a plurality of excitation windings is widely known and employed as a stepping motor (pulse motor or step motor). Stepping motors have a long lifespan because they do not have mechanical moving parts such as brushes, and the number of applied pulses matches the rotation angle, causing no cumulative errors, so they are used as positioning mechanisms without feedback circuits.

As mentioned above, a stepping motor rotates a rotor by a fixed angle by sequentially applying pulses to a plurality of excitation windings, but since pulses are applied to each winding in a complicated manner, the pulse current generates heat. The heat-resistant life of the winding becomes a problem.

GHP (GAS) is one of the application examples of stepping motors.
There is an ENGINE I (EAT PUMP) system. The GHP system uses regular city gas as engine fuel to rotate a heat pump to supply hot water, air conditioning, and heating, and in order to maintain high efficiency, the engine speed must be kept constant at all times. In this system, the engine speed is normally kept almost constant, but it often fluctuates due to subtle load fluctuations (refrigerant gas, etc.) or disturbances in the intake gas. It becomes necessary to detect fluctuations in engine speed (deviation from a constant value) and adjust the amount supplied to the engine by controlling the opening angle of the throttle valve.

(Problems to be Solved by the Invention) In systems (not limited to the above-mentioned GHP system) that have a function of maintaining a constant engine speed, as described above, problems occur due to the supply of pulsed current to the excitation winding. Heat shortens lifespan. In particular, in the GHP system, the engine speed does not change much at all times, so the throttle valve is often kept at a constant opening and stopped. It is wasteful to supply pulsed current to a plurality of excitation windings, and there is also a problem in terms of power consumption.

Conventionally, measures to reduce the current consumption that causes heat generation include (1) lowering the motor drive voltage, (2) stopping the supply of pulse current when the motor is stopped, and (3) increasing the winding resistance. However, there is a risk that the initial torque when driving the motor may not be sufficiently satisfied, and it is difficult to provide sufficient stopping torque necessary to maintain the throttle valve in the stopping position. For these reasons, this was not necessarily a desirable measure.

In addition, methods such as using a heat-resistant winding wire as a winding material or cooling the winding wire may be considered in order to improve the lifespan, but these methods increase costs and are not preferred.

(Means for Solving the Problems) This invention was made against the background of the above circumstances, and is a stepping motor that rotates the motor by sequentially changing the combination pattern of currents supplied to a plurality of excitation windings. The driving method is characterized in that a current pattern supplied when the motor is stopped is set to a pattern in which current is supplied only to one excitation winding among the plurality of excitation windings.

(Function) In this invention, since the stepping motor is stopped by one-phase excitation when it is stopped, the current consumption is reduced when it is stopped.
The motor's self-temperature rise can be reduced.

(Example) Next, an example of the present invention will be described in detail based on the accompanying drawings.

The present invention is a stepping motor driving method, and various application examples are possible, but an application example to the aforementioned GHP system will be described here.

FIG. 11 shows the configuration of the main parts of a GHP system showing an embodiment of the present invention. In FIG. The amount of fuel (!IA city gas) supplied to the engine 3 side is adjusted. The city gas that has passed through the fuel valve 2 is mixed with air and exhaust gas components from an EGR (exhaust gas recirculation system) in a mixer 4, and is sent into the combustion chamber 6 of the engine 3 via an intake passage 5. Exhaust gas obtained by combustion of the mixed gas in the combustion chamber 6 is discharged from the exhaust passage 7 via the exhaust muffler 8.

A part of this exhaust gas is taken out from the exhaust system, controlled by temperature, timing, flow rate, etc., recirculated to the intake system, and returned to the mixer 4. The intake passage 5 is opened and closed by the intake valve 9.
The exhaust passage 7 is opened and closed by an exhaust valve IO.

The mixed gas is supplied to the engine 3 with its amount controlled by a throttle valve 11. The opening degree of the throttle valve 11 is controlled to maintain the rotational speed of the engine 3 constant. That is, as described above, fluctuations in engine speed due to load fluctuations, disturbances in intake air amount, etc. are detected via the signal line 13 using a detection signal from the crank rotation sensor 12.

Based on this detection signal, the engine control unit 2 controls the stepping motor 14 as a driving means for the throttle valve 11. The engine control unit 2 receives the output of the cooling water temperature sensor 15 and the output of the oil level sensor 16 from the engine 3, in addition to controlling to maintain a constant engine speed, and controls various engine systems.

When the side light is on, the engine control unit 2 sends an optimal ignition timing signal to the ignition plug 18 via the ignition coil 17.

For example, in the configuration shown in FIG. 1, the present invention provides an opening angle control that reduces power consumption of the throttle valve 17, and supplies drive pulses to the excitation winding of the stepping motor 14 in a single-phase drive when stopped. This is made possible by

Hereinafter, specific examples will be described in detail.

FIG. 2 is a configuration diagram of the engine control unit 2 and the stepping motor 14. The engine control unit 2 uses DC +12V as an input power source, and the CPU (
For example, a power supply circuit 21 that outputs +5V DC power for operation (for example, an L-chip 8-bit microcomputer) receives output from a crank rotation sensor 12 (engine pulse pickup coil) for detecting engine rotation speed, and detects the engine rotation speed. The engine pulse input circuit 23 supplies a rotational speed signal indicating the engine temperature to the CPU 22, the output of the cooling water temperature sensor 15 indicating the engine engine temperature, and various status output signals such as the output of the engine oil level sensor 16 are received.
22.

The CPU 22 continuously operates based on a clock signal of a predetermined frequency from the oscillation circuit 25. The CPU 22 compares the current engine speed with a predetermined reference speed, and when a difference occurs between the two engine speeds, the stepping motor 14 is switched to the stepping motor drive circuit 26 in order to make the difference zero.
Rotation control via.

The stepping motor 14 is a four-phase motor with four excitation windings.
Taking an example with @, the input terminal 141.1 to each excitation winding
Stepping motor drive circuit 2 at 42, 143, 144
6, pulses in different pulse sequence formats are sequentially sent out.

In FIG. 3, a timing chart of signals supplied to each terminal 141 to N144 in order to rotate the stepping motor 14 at a constant speed is shown in chronological order in response to the clock from the oscillation circuit 25. In FIG. 3, the numbers 1 to 9 at the top indicate the number of clocks, and a pulse sequence is determined for each number state.

FIG. 4 shows an example of the configuration of the stepping motor drive circuit 26. Output terminals PO, PL, P of CPU22
2. From P3, a signal supporting the signal to be applied to each excitation winding for driving the stepping motor is input to the stepping motor drive circuit 26. The stepping motor drive circuit 26 is connected to each drive circuit 2 of the stepping motor 14.
6 through backflow blocking diodes 145, 146, 147 and 148. Pulse supplied to each excitation winding (HIGH level signal rHJ or f I J
The stepping motor 14 is rotated in a predetermined direction by predetermining the sequence of the LOW level signal rLJ and (represented by *rOJ). FIG. 5 shows an example of the sequence of pulse signals supplied from each CPU output port PO to P4 in the case of a four-phase motor.

At this time, as is well known and as is clear from FIG. 5, one-phase excitation and two-phase excitation are repeated alternately (usually referred to as one- to two-phase excitation). If the pulse sequence for instructing the throttle valve stop position is set so that the throttle valve is always in the l-phase excitation state, the current consumption during stop will be halved compared to two-phase excitation. Therefore, the heat generated is also significantly reduced.

This invention focuses on this point, and in this example, the state θ
7, the even number states $0.2 and $4.6 result in l-phase excitation, so it can be seen that the state of the pulse sequence for stopping the throttle valve should be set to an even number state. In addition, in this example, an even numbered state is selected and set for one-phase excitation, but if each port output pulse is based on pulse sequence change regulation based on each state transition, it can be set to an odd numbered state. It is clear that the same is true.

In short, the stepping motor should be excited in l-phase when stopped.

Next, the procedure of stepping motor drive control for throttle valve opening control in this embodiment will be specifically explained.

Since the stepping motor 14 is a relative position change control means, it is necessary to determine its absolute position. First, the initial position of the throttle knob 11 is determined. As a determining means, in this embodiment, a stopper 31 corresponding to the fully open position and the fully closed position of the throttle valve 11 is provided, as shown in FIGS. 6 to 9. Throttle/(Lube 11 when fully closed (Figure 8) and fully open (Figure $9)
The state of the stepping motor 14 is set as the initial state, and the pulse sequence in this initial state is expressed as the initial value of the angle (
For example, the opening angle of the throttle valve is controlled from this initial value.

In FIGS. 6 and 7, the rotational force of the stepping motor 14 is transmitted via a rod 32 to a connecting member 34 connected to a shaft 33 of the throttle valve 11, which rotates the throttle valve 11. The rotation angle is usually about 70 degrees, but the rotation angle is 90 degrees so that the stopper 31 is always in contact with the stopper holder 35.
It is set to In this way, the stepping motor 14
The initial position of the throttle valve 11 is determined, and the opening angle of the throttle valve 11 is set from the initial position as follows.

The basic control flow is as shown in Figure 1θ. First, as mentioned above, after detecting the fully closed position, that position is used as the initial position and the opening degree D0 is set, and the pulse sequence is created in chronological order. Set the clock number i to 0 (step a). Next, set the fully open position to 0.
After checking with the fully open stopper explained in the figure and performing an initial confirmation of the operation (step b), constant control of the engine speed N is started (steps c and d), that is, the current engine speed N is and the predetermined reference rotation speed N
Based on ref, a control signal for the throttle valve opening is determined so that the deviation between the two becomes zero. This control signal Vr
ef is usually determined by the following formula based on so-called PID control.

Vref=P+I+D+offset Here, P is a proportional term, [Nref-N] ・Kp■
is an integral term, [Σ(Nref-N)] K i D is a differential term, and [N-N (pgst)] Kd (Kd, Ki, Kd are coefficients) The control signal obtained in this way is the corresponding throttle The signal is supplied to the stepping motor drive circuit 26 to adjust the opening angle of the valve 11.

On the other hand, if the engine speed N matches the reference value Nref and the throttle valve is to be stopped, select the pulse sequence for l-phase excitation 1. Set. In this embodiment, as described above, when the state number is an even number, l-phase excitation is performed, so if the state number is controlled to be an even number, power consumption can be reduced. In this embodiment, the stepping motor 14 is driven by an 8-bit signal, and the LSB of the 8-bit signal is reset to 0 in order to make the state number even when stopped (step d).

FIG. 121 and FIG. 13 show the flow of the expected state of stepping motor drive as described above.
In the figure, the target value is set to 0 degrees after fully closed detection, and the current value is set to 90 degrees based on the forced rotation angle of the stepping motor 14.
After setting the angle to 10.3°, the process returns to the predetermined processing procedure. Also,
In FIG. 13, after the initial operation, the target value is set to 70°1 based on the actual rotation angle of 70° of the stepping motor 14.
After setting it to 0.3 degrees, set the target value to 0 degrees. Further, the target value is set to the starting opening degree of 10.3°, and the process returns to the predetermined processing procedure.

FIG. 11 shows that when state number i is indicated by an 8-bit signal,
A flowchart is shown for driving the stepping motor 14 to drive the throttle valve opening to a target value.

This flowchart operation compares the target value rotation speed Nref determined in step C of FIG. 10 with the current rotation speed N and calculates the difference. Control proceeds to step i so as to maintain the condition. When (Nref-N) is positive, the state number i is increased to i+1 in step g in order to rotate the throttle valve 11 by one more step, and then the process moves to step i. On the other hand, when Nref-N is negative, i is set to i-1 in order to rotate in the opposite direction, and then the process moves to step i. Stiffness treatment is step f
This is done on the basis of In step i, state number i is the fifth
As shown in the figure, the process corresponding to the input data to each of the eight ports is performed by performing AND logic between i and $07, and is output as j. The operation pulse pattern PCOD (j) thus determined is obtained in step j, and the opening degree of the throttle valve 11 is controlled. This is repeated in the same manner in subsequent opening degree control.

(Effects of the Invention) As described above, according to the present invention, when controlling the stepping motor drive, the motor is configured to be stopped by one-phase excitation, so power consumption during stopping is reduced, and the excitation winding is The heat-resistant life of the product is greatly improved. In particular, a significant improvement effect can be expected when the stepping motor is often used in a stopped state, such as in a GHP system in which a stepping motor is used to control the opening of a throttle valve.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of main parts of a GHP system showing an example of application of the present invention, Fig. 2 is a block diagram of an engine control unit and a stepping motor, Fig. 3 is a signal time chart for operation of the stepping motor, and Fig. 4 is FIG. 5 is a stepping motor drive circuit diagram, and FIG. 5 is an operation pattern diagram of the stepping motor. 6 to 9 are diagrams showing the relationship between the stepping motor and the throttle valve, and FIGS. 10 to 13 are control flowcharts of the slow 7 torque valve by the stepping motor. l...Fuel valve 2...Engine control unit 11...Throttle valve 12...Crank rotation sensor 14-...Stepping motor 23...Engine pulse input circuit 24...Sensor input circuit 25...・Oscillation circuit 26...When stepping motor drive circuit Applicant: Yama/\Tsuru, Patent Attorney, Motor Co., Ltd.
Waka Toshio Figure 3, +゛j i, il: i input +141 λ power discussion) 144 Figure 4 @5 Figure 6 Figure 6. Figure 8 z No. 9

Claims (1)

[Claims] In a stepping motor driving method in which a motor is rotationally driven by sequentially changing a combination pattern of currents supplied to a plurality of excitation windings, the combination pattern of currents supplied when the motor is stopped is changed to a combination pattern of currents supplied to the plurality of excitation windings. A method for driving a stepping motor, comprising setting a pattern in which current is supplied to only one of the excitation windings.