JPH03265488A - Motor drive circuit - Google Patents

Abstract

PURPOSE:To shorten start and stop times of a motor and to drive the motor with low power consumption by subjecting a rotational speed control signal to chopper control only during constant speed rotation interval except starting interval of motor. CONSTITUTION:Upon turn ON of a motor, a maximum current 10 flows alternately through coils Cu, Cv, Cw and a rotor is accelerated. At that time, a rotational speed lock signal 7 has High level and a gate circuit 41 is closed and thereby a switching circuit 42 remains in ON state thus bringing the motor into constant speed rotational state in a shortest time. When the rotational speed lock signal 7 goes Low, the gate circuit 41 is opened and the switching circuit 42 chops the rotational speed control signal with the frequency of the oscillation circuit 42 thus feeding current intermittently through the coils Cu, Cv, Cw. A current 12 flows during conducting interval and the average current will become I0.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motor drive circuit, and particularly to a motor drive circuit comprising a rotating magnet, an armature coil, and a fixed yoke.

[Prior Art 1] FIGS. 4(A) and 4(B) show a conventional drying and drying drive circuit. FIG. 4(A) shows a drive circuit for a three-phase semiconductor motor. In the figure, the symbol l is a motor drive IC, the symbol CI is a power supply stabilization capacitor, and the symbols Hu, Hv
, I-(w is a Hall sensor for detecting the rotation angle of a rotor (not shown) and determining the energization timing of the drive coils Cv, Cu, and Cw; symbols R1 and R2 determine the bias current input to the Hall element. The motor drive circuit 1 is controlled by a motor on/off signal input from a signal line 8.

Reference numeral 7 is a rotation speed lock signal output, and when the motor is within a certain range with respect to the target rotation speed, the rotation speed lock signal is output. Reference numeral 6 denotes an integrator that integrates the phase comparison output 9 of the PLI-control circuit. The integrated signal is inputted again to the motor drive circuit 1 through the phase compensation circuit 3, and becomes a coil drive signal.

Next, the operation of the motor will be explained with reference to FIG. 4(B). When the motor is turned on at time tl, current 0 flows through the drive coil and the rotor accelerates.

When the rotation speed of the rotor approaches the target value, the rotation speed lock signal becomes a low level at time t], and the motor is driven at a constant speed. A current 11 flows through the drive coil.

When the brake is applied at time t2, current IO flows through the drive coil, causing the rotor to decelerate and stop at time t3.

The current 11 during constant speed rotation is K, where the torque constant is KO and the load torque is TO.

becomes. From this equation, it can be seen that the rated load current can be reduced by increasing the torque constant KO.

[Problems to be Solved by the Invention] However, in the conventional example described above, since the resistance value of the drive coil increases when the torque constant KO is increased, there are the following drawbacks.

(1) Since the maximum torque is limited, starting and braking times become longer.

(2) Since the coil resistance changes with temperature, the temperature dependence of starting and braking times increases.

Therefore, there was a problem in that the power consumption of the motor could not be kept low.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a motor drive circuit that can shorten the start and stop times of the motor and drive the motor with low power consumption.

[Measures to Solve the Problems IR] In order to solve the above problems, the present invention provides a motor drive circuit including a rotating magnet, an armature coil, and a fixed yoke. A configuration was adopted in which the rotation speed control signal is chopper-controlled only during periods of high speed rotation.

[Function] According to the above configuration, power consumption can be reduced by chopper control during the constant speed rotation period, and since chopper control is not performed during the startup period, startup can be performed quickly.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

First Embodiment FIG. 1 shows a circuit block diagram of a first embodiment according to the present invention. In the figure, explanations of members and operations common to the conventional example are omitted.

What is different from the conventional example shown in Fig. 4 in Fig. 1 is the chopper circuit 4.
The point is that an oscillation circuit is provided.

The chopper circuit 4 is composed of a gate 41 and a switching element 42 based on a rotation speed lock output.

Next, the driving operation of the motor according to the present invention will be explained using FIGS. 1 and 2 (A), (B), and (C).

When the motor is turned on at time to, the coils Cu, Cv, and Cw
The maximum current IO flows alternately in and the rotor starts accelerating. At this time, the rotation speed lock signal 7 is at a high level and the gate circuit 41 is closed, so the switching circuit 42 remains on.

The motor will be in constant speed rotation in the shortest possible time.

When the rotation lock signal becomes low level, the gate circuit 41 opens and the switching circuit 42 chops the rotation speed control signal at the frequency f of the oscillation circuit 2, so that the coils Cu and Cv
, Cw becomes intermittent as shown in FIG. 2(C). A current I2 flows during the energization period, and a current IO flows on average.

Now consider the loss of the output stage transistor during constant speed rotation. The voltage between the collector and emitter of the output stage transistor is V
Assuming CE, the collector-emitter voltage when the currents are II and 13 is I l < I 3, so VCE (I
3) <VCE(I 1).

Since the collector-emitter voltage is low, the loss is smaller in the embodiment shown in FIG. 1 when considered in average value. Assuming that the loss of the conventional example in Fig. 4 is IIVCE (11) and the loss of this embodiment is Ploss (I3), by changing the duty ratio of the oscillation circuit, Ploss (I 3) < I IVCE (I l)
- (2) can be set. Considering the average current I2, I2<I1. The frequency of the oscillation circuit 2 is a frequency f(
f, zlOfO).

As described above, by chopper-controlling the rotational speed control signal only during the constant speed rotation, the corephthal emitter loss of the output stage 1 helangister can be reduced, and the power consumption of the motor can be reduced.

Second Embodiment FIG. 3(A) shows a second embodiment of the present invention. The difference in this embodiment from the first embodiment is the chopper circuit 5.
The motor drive circuit 1 is a phase comparator type PL in that it does not include a gate circuit, and that it uses the logical sum of the phase comparison output 9 and the rotation speed lock signal 7 as a switching signal.
It can be configured as long as it has an LII@ circuit.

The chopper circuit 5 in FIG. 3(A) is controlled to close when the OR output a is at a high level. As a result, maximum torque is generated from startup to constant speed rotation and from braking to stopping, making it possible to start and stop in the shortest possible time.

As is clear from the timing chart in FIG. 3(B), in this embodiment, the chopper control is performed during constant speed rotation, so the chopper duty ratio and current flow settle at stable values. The power consumption of the motor is the same as in the first embodiment.
If the power consumption of the conventional motor is Po1d, and the power consumption of this embodiment is P new2, then P new2< P old ・=
(3) becomes.

Even with such a configuration, the same effects as in the embodiment described above can be expected.

[Effects of the Invention] As is clear from the above, according to the present invention, in a motor drive circuit including a rotating magnet, an armature coil, and a fixed yoke, the motor rotates only during the constant speed rotation period excluding the startup period. Since the configuration employs chopper control of the number control signal, power consumption can be reduced by chopper control during the constant speed rotation period, and since chopper control is not performed during the startup period, startup can be performed quickly and the motor startup time can be reduced. This has the excellent effect of making it possible to shorten the length of time and driving the motor with low power consumption.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a motor drive circuit according to a first embodiment of the present invention, and FIGS. 2 (A) to (C) are rotation speed locks from motor startup to constant speed rotation in the circuit of FIG. 1. FIG. 3(A) is a timing chart diagram showing signals, rotational speeds, and currents, and FIG. 3(A) is a block diagram showing the configuration of a motor drive circuit according to a second embodiment of the present invention.
B) is a timing diagram showing the motor operation by the same circuit, FIG. 4(A) is a block diagram showing the configuration of a conventional motor drive circuit, and FIG. 4(B) is a timing chart showing the motor operation in the circuit of FIG. 4(A). FIG. 3 is a timing chart showing the state of the motor from starting to constant speed rotation to stopping. 1... Motor drive circuit 2... Oscillation circuit 3...
Phase compensation circuit 4.5 - Chopper circuit Fig. 3 (
A) t. 1 fermentation t. 1 It's closing at 7-9. 1 o'clock closing mo, -1fI'J 11, 1〈Fuimi〉France〉Figure 3 CB) di's ε-Mauma ¥1mi! 7 is Eid (former Figure 4 CB)

Claims (1)

[Scope of Claims] 1) In a motor drive circuit comprising a rotating magnet, an armature coil, and a fixed yoke, the rotation speed control signal is chopper-controlled only during a constant speed rotation period excluding a motor startup period. motor drive circuit. 2) The motor drive circuit according to claim 1, wherein the timing at which the chopper circuit that controls the chopper is switched between operation and non-operation is synchronized with a rotation speed lock signal. 3) The motor drive circuit according to claim 1 or 2, wherein the switching signal for the chopper circuit is generated by an oscillation circuit. 4) The motor drive circuit according to any one of claims 1 to 3, wherein the switching signal of the chopper circuit is an output of a phase comparator of a PLL rotation speed control circuit.