JPH04299090A - Starting method for dc motor - Google Patents

Abstract

PURPOSE:To shorten the starting time by performing the switching so that a resistor is connected in parallel with a load resistor and the load resistance is decreased only at the starting time. CONSTITUTION:Output pulse signal(PL) from a DC motor 6 is compared with a reference value WR. Output signal from a speed comparator 10 switches a load resistor 7. Output signal from a PLL circuit 9 is inputted, as a full acceleration instruction, to a preamplifier 4 at the time of starting. The pulse output signal(PL) fed to the speed comparator 10 is compared with a speed comparison reference signal W' in order to decide the starting time. At that time, output signal from the speed comparator 10 functions on a transistor Q3 in a power amplifier 5 so that a resistor RD2 is connected in parallel with a load resistor RD1. Consequently, the load resistor 7 i.e., the combined resistor of RD1 and RD2, is connected in series with the DC motor 6 and the value of the load resistor RD<1> is switched.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit for a DC motor, and more particularly to a method for starting a DC motor.

0002

2. Description of the Related Art FIG. 4 is a block diagram of a conventional DC motor control circuit, and FIG. 5 is a specific DC motor control circuit diagram of the PLL control circuit system shown in FIG. The DC motor control circuit is
It is composed of a speed error detector 1, a position error detector 2, an adder 3, a preamplifier 4, a power amplifier 5, a load resistor 7 (RD), and a motor pulse generator 8 using a DC motor 6. Output signal PL of this motor pulse generator 8
is fed back to the speed error detector 1 and the position error detector 2, and the speed error detection output and the position error detection output, which are compared with the target values ωR and θR, are added in the adder 3, and then the preamplifier 4 and the power amplifier amplified by 5,
It is output to the DC motor 6 and speed control is performed. When this speed control is being performed, the DC A load resistor (Fig. 5) connected in series to the motor 6
It was necessary to increase RD (shown in Figure 1). Figure 5
9 is a PLL circuit, V1 is a stabilized power supply, and V2 is a power supply, and generally V1<V2.

0003

However, as shown in FIG. 6, when the load resistance RD is large, a sufficient starting current cannot flow, resulting in a disadvantage that the starting time becomes long. In view of the above-mentioned points, the present invention provides a DC motor starting method that effectively solves the problems of the prior art and shortens the starting time without deteriorating the S/N ratio during speed control. That's true.

0004

[Means for Solving the Problems] In order to achieve the above object, the present invention has a speed error detector and a position error detector, and adds the outputs of the speed error detector and the position error detector. A DC motor control circuit that controls the speed of a DC motor, wherein a load resistance value provided to the DC motor is switched at the time of startup by an output signal of a speed comparison circuit provided in the DC motor control circuit. This is the startup method.

[0005]

[Operation] By adopting the DC motor starting method of the present invention, it is not necessary to perform speed control at the time of starting, so it is possible to reduce the load resistance. Therefore, in order to reduce the load resistance only at the time of starting, By switching to insert a resistor in parallel with the load resistor, S during speed control can be reduced.
To shorten startup time without deteriorating /N ratio.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a block diagram of a DC motor starting circuit according to the present invention, and FIG. 2 shows a specific circuit diagram of FIG. The DC motor starting circuit includes a speed comparator 1 in the DC motor control circuit shown in Figure 4.
0 is given, and the motor pulse output signal PL from the DC motor 6 is compared with a predetermined reference value WR. The load resistor 7 is switched based on the output signal of the speed comparator 10. As shown in FIG. 2, according to the PLL control method, the PLL circuit 9
At startup, the output signal becomes a full acceleration command and is input to the preamplifier 4. The motor pulse signal PL input to the speed comparator 10 is compared with the speed comparison reference signal ω'0, and it is determined that it is the start time. At this time, Figure 2
As shown in , when it is determined that it is time to start, the speed comparator 1
The output signal of 0 acts on the transistor Q3 of the power amplifier 5, and the resistor RD2 operates in parallel with the load resistor RD1. As a result, the load resistor 7 (FIG. 1) connected in series to the DC motor 6 becomes a composite resistance of the resistors RD1 and RD2, and the value of the load resistor RD1 is switched. FIG. 3 shows a timing chart for the case of FIG. As shown in the figure, the time required for the motor current to arrive by the control reference signal ω0 of the DC motor 6 is shortened, and the starting time is shortened. VD shown in FIGS. 2 and 3 is the voltage applied to the load resistance. Therefore, S when controlling the speed of the DC motor 6
It is possible to shorten the startup time without deteriorating the /N ratio. Note that the present invention is not limited to the above embodiments, but can be modified by appropriately making design changes.
It can also be implemented in other embodiments.

[0007]

[Effects of the Invention] As is already clear from the above explanation, the method for starting a DC motor of the present invention does not require speed control at the time of starting, so it is possible to reduce the load resistance, and only at the time of starting. In order to reduce the load resistance, by switching to insert a resistor in parallel with the load resistance,
The problems of the conventional technology have been effectively solved, and the S/
This provides effects such as shortening the startup time without deteriorating the N ratio.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a DC motor starting circuit of the present invention.

FIG. 2 is a specific circuit diagram of FIG. 1;

FIG. 3 is a timing chart in the case of FIG. 2;

FIG. 4 is a block diagram of a control circuit for a DC motor.

FIG. 5 is a specific circuit diagram of FIG. 4;

FIG. 6 is a timing chart in the case of FIG. 5;

[Explanation of symbols]

1 Speed error detector 2 Position error detector 5 Power amplifier 6 DC motor 7 Load resistance 9 PLL circuit 10 Speed comparator

Claims (1)

[Claims] 1. A DC motor control circuit that has a speed error detector and a position error detector and controls the speed of a DC motor by adding outputs of the speed error detector and the position error detector, wherein the DC motor control circuit The DC motor is characterized in that a load resistance value provided in the DC motor is switched at the time of startup by an output signal of a speed comparison circuit provided in the circuit.
How to start the motor.