JPH0240045A - Control method for step motor for driving throttle valve - Google Patents

Abstract

PURPOSE:To perform reversing without overshooting and a delay by a method wherein when a step motor is reversed, a time of a present exciting phase is prolonged by a time longer than an approximate half period of shortmost free vibration, and reversing excitation is effected after a speed phase is reversed due to free vibration. CONSTITUTION:In a block 1, when the present position of a rotor is compared with a target phase and reversing is effected and decision is made to perform reversing, starting from a stop is executed when a motor is not under high speed running. When it is under high speed running, and when a speed is, for example, 1/2 pulse/sec (PPS) of maximum free vibration and exceeds 600 PPS, excitation is held, and the phase of a speed is inverted with free vibration. Phase inversion occurs at intervals of approximate a half period of free vibration since a deviation between a speed under continuous drive and a position is approximately specified and a speed coincides with a drive direction even when free vibration is started. In a block 4, a time of a present exciting phase is prolonged by a time longer than an approximate half period of shortmost free vibration, and reversing excitation is effected after a speed phase is reversed due to free vibration. This constitution enables execution of reversing without an overshooting amount and a delay time.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a step motor control method for driving a throttle valve, and more particularly to a control method for smoothly performing rapid reverse rotation.

<Prior Art and its Problems> A throttle valve that controls the amount of air supplied to a vehicle engine requires minute opening/closing control, and is therefore controlled by being connected to a step motor and a speed reduction system. This throttle valve driving motor (hereinafter referred to as motor) is required to follow the target position determined by the accelerator position and torque command value without delay. In this case, the motor can easily control the position that changes every moment, in other words, it performs open loop control that does not require position feedback, and is suitable for throttle valve control, but there is a high possibility of tax adjustment when there is a sudden reversal.

In order to prevent tax adjustments caused by such sudden reversals, conventionally, as shown in Figure 6, when a reversal instruction is received, the motor is decelerated, stopped, then reverse rotation is started, and normal reversal is performed after acceleration from low speed. We are performing a reversal of the steps to be taken.

However, with this method, the throttle opening changes even when the motor decelerates after a reverse rotation instruction, and the
The time for slow reversal results in an overshoot and also a time delay for normal reversal recovery.

Additionally, to prevent tax adjustment, as shown in Figure 7, there is a method in which the reverse rotation is instructed to stop once, wait until the vibration subsides, and then reverse the rotation, but in this case, it is necessary to allow sufficient vibration damping time. There is a huge time delay.

In order to solve these problems, the present invention provides a step motor control method for driving a throttle valve that enables rapid reversal without causing overshoot and with only a slight time delay.

<Means for Solving the Problems> The present invention, which achieves the above-mentioned objects, extends the current excitation phase time longer than about half the period of the shortest free vibration when reversing the step motor that drives the opening and closing of the throttle valve. ,
The present invention is characterized in that the reverse excitation is performed after waiting for the speed phase to reverse due to this free vibration.

<Function> By fixing the excitation phase, when reverse excitation is performed when the speed phase generated by free vibration is reversed, the drive direction and motion direction match, and operation can be started immediately without tax adjustment. .

Here, to illustrate the state of torque, free vibration, and subsequent step-out when the excitation of the motor is fixed, as shown in FIG.
The magnet has a characteristic of having a maximum and a minimum of 1 to 100 kW, and when the excitation is fixed (stopped), the free vibration shown in FIG. 9 is generated.

Looking at it in this way, as the relative phase deviation of the rotor to the motor stator increases, the torque increases accordingly, and if an external force is applied to the rotor at the peak of a step response wave with a large positional deviation, it will easily step out. It turns out that.

If we consider the case of step-out due to reverse rotation, as shown in Figure 10, when driving a step motor using pulses, there is a characteristic in which the positional deviation reciprocates around O, and the rotor angular velocity also changes. Taking this into consideration, for example, a driving characteristic can be obtained that depicts a clockwise rotation loop as shown by the arrow, but due to this driving characteristic, if reverse rotation is started immediately at point R, position deviation will occur suddenly if the speed and reverse driving direction do not match. It increases and moves to the tax control area.

As a result of considering the behavior associated with such a tax adjustment, the present inventor found that if the tax adjustment caused by reverse excitation in the first quadrant state shown in FIG. We have found that it can be used to the maximum extent, i.e.,
If reverse excitation is performed during vibration in the opposite direction to the driving direction, reverse rotation will be possible without step-out. That is, Fig. 11 (a
), in the dark region of forward rotation where the position error is ±Δθ across zero, the excitation phase is fixed to enable reversal, and after a certain period of time the motor is in a state of free vibration, the motor is reversely excited. do. This reverse excitation is shown in Figure 11 (a) when the phase of the velocity of free vibration is reversed as shown in Figure 11 (b).
) smoothly transitions to the reversal region. In this case, since free vibration is used, the excitation phase identification time shown in FIG. 11(b) is constant and ≠period of resonance.

The results of a control simulation using such a method are shown in Figure 12 (al). In this Figure 12 (al), the highest waveform is the torque, the middle waveform is the position deviation, and the lowest waveform is the rotor angular velocity. When the step motor is started, θ increases, and a reverse rotation command is issued during operation in the uppermost loop L to cause free vibration, and the phase of the speed is reversed and reverse rotation is started, the transition to the third quadrant occurs.

That is, in FIG. 12 F, 1, not only the torque and positional deviation change before and after the stop period, but also the speed transfer θ is reversed. A typical motor has a resonant frequency of 1.30 Hz to 1
Since the frequency is 80 Hz, the control delay in this simulation is 2.5 m5ec to 3.5 m5ec, and a slight reversal of the delay is possible without tax adjustment.

<Example> Here, an example of the method of the present invention will be described with reference to FIGS. 1 to 5. Figure 1 shows the motor drive method, continuous rotation,
The flow is divided into cases of immediate reversal and starting from a stop.

Inside the computer, the current position of the rotor is first compared with the @ mark position to determine the state change in the driving direction (
Block 1). As a result, when continuing rotation in the same direction, the block 2 does not generate pulses equal to the number of drive steps.
),continue.

Next, if the reverse rotation is to be performed based on the determination in block 1, it is determined whether or not high-speed driving is currently being performed (block 3).If high-speed driving is not currently being performed, the flow shifts to a start-up flow from a stop, which will be described later.

When driving at high speed, for example, at a maximum self-starting speed of about v2pps (pulse 7 seconds) - for example, at a speed of 600 PPS or more, even if a reverse command is issued, it is difficult to reverse the reverse phase at high speed.
While excitation is maintained, the phase of velocity is reversed by free vibration. This phase reversal occurs after half a period of free vibration because the speed and positional deviation are approximately constant during continuous driving, and even when free vibration starts, the speed is consistent with the driving direction.

By performing reverse excitation after this, it is possible to match the driving direction and the movement direction and prevent tax adjustment. In other words, based on the high-speed drive determination result in block 3, the process moves to reversal processing after phase reversal.
(Block 4) According to this processing command, first, in order to determine the timing of the anti-phase period of free vibration, first, the excitation time TP of the current phase is set to the free vibration holding time which is 0.5 to 0.8 times the free vibration period. Obtain the excitation holding time Th of the current phase by subtracting it from T9 (block 5), and then use the timer to hold the excitation of the current phase for this time Th (block 6).
, this timer generates a backward drive pulse for a holding time (block 7) to perform reverse excitation.

When starting from a stop, which cannot be started immediately by restarting including reverse rotation, first, in block 8, it is determined whether it is a complete stop, a stop from a low speed, or a low speed drive.Specifically, 7! l), it is determined whether it is stopped at 600 PPS or less or is being driven at 600 PPS or less. If these conditions are met, immediate reversal (activation) is performed without the risk of tax adjustment (block 9). Then, a drive pulse similar to that in block 2 is generated (block 10). If stopping from a complete stop and low speed and driving at low speed are not satisfied in block 8, the phase of the speed is checked based on the time from the start of stop excitation, and it is determined whether it is the same as or opposite to the next rotation direction (block 11). In the same case, the process moves to block 9 and starts immediately, but in the judgment of block 11, ζ is changed to ζ as shown in Figure 1 (C1), and the excitation time Tp of the current phase is changed to the vibration period Tc shown in Figure 2. Assuming that the remainder after division is τ, block lla calculates τ, and when it is larger than the required holding time TS for free vibration, it is reversed (block 1lb), and when it is smaller than the required holding time T9, it is rotated normally (block 11c).
). When the conditions of blocks llb and lie are not met, wait for speed reversal and perform reversal (startup).
Block 12). Thereafter, in block 13, the holding time is calculated in the same manner as in block 5, and based on Th-T, -τ, the process moves to block 6, which lends the excitation of the current phase for Th period. An example of how the system restarts after being stopped is illustrated in FIG.

The flow of the control method has been described above, and FIG. 4 shows a simplified configuration of the control device. In FIG. 4, the computer incorporates a rotation direction designation logic 20 and an excitation time designation logic 21, and the forward/reverse switching section 22 is controlled by this rotation direction designation logic 20. When the timer 23 is activated by changing the excitation time designation logic 21, the forward/reverse switching section 22 switches to the above-mentioned time T7. The switching timing is determined by counting. Excitation switching is based on the excitation phase table 24, for example, in two types of windings: A direction, X direction (opposite to A), and B direction.
A current in direction U (opposite to B) is passed, and forward or reverse rotation is performed.

Fig. 5 is an example of a reversal possibility determination circuit for showing a method different from the method shown in Fig. 1, in which the position is differentiated to obtain the speed, and the deviation between the position where the drive pulse is integrated and the current position is calculated. By obtaining this, it is determined whether or not the rotation can be reversed based on the velocity-position deviation coordinates, and if the upper body is safe, the rotation will be performed.

<Effects of the Invention> As explained above, according to the present invention, reversal can be performed without overtravel or delay time as in the conventional case, and in particular, it can be realized without changing the current hardware, and high-speed drive can be achieved from the beginning. is possible and requires few changes to the software.

[Brief explanation of the drawing]

Figure 1 (a) (b) (El is a flow diagram of an embodiment of the method of the present invention, Figure 2 is a waveform diagram specifying the speed phase, Figure 3 is a waveform diagram that does not show restarting from a stop, Figure 4 is a simplified configuration diagram of the control circuit, Figure 5 is a diagram showing another control method, Figures 6 and 7 are the waveforms of the conventional reversing method, 1 to 13 are functional blocks, and 20 is rotation direction designation logic. , 21 is an excitation time designation logic, 22 is a forward/reverse switching unit, 23 is a timer, and 24 is an excitation phase table.

Claims (1)

[Claims] When reversing the step motor that drives the throttle valve to open and close, extend the current excitation phase time longer than approximately half the period of the shortest free vibration, and wait for the speed phase to reverse due to this free vibration before performing reverse excitation. A step motor control method for driving a throttle valve.