JPH05292785A - Dc motor driver - Google Patents

Abstract

PURPOSE:To make compact a DC motor driver by providing a pulse modulator producing a pulse corresponding to a torque command signal, a Hall effect element corresponding to an exciting coil onto which a pulse signal is applied from the pulse modulator, and a power amplifier for amplifying an output from the Hall effect element and applying onto the exciting coil. CONSTITUTION:A torque command signal is fed from an input terminal 1 through an absolute value circuit 6 to a pulse width modulator 3. Pulse output from the pulse width modulator 3 is fed through a direction switch 7 to Hall effect elements 2a-2c corresponding with exciting coils 5a-5c. Outputs from the Hall-effect elements 2a-2c are applied onto power amplifiers 4a-4c corresponding with the exciting coils 5a-5c. At the same time, polarity of torque command signal being applied on the input terminal 1 is decided through a polarity decision circuit 8 and the direction switch 7 is switched depending on the decision result. Consequently, the number of necessary pulse width modulator and associated absolute value circuit, polarity decision circuit, and direction switching circuit can be set, respectively, at once.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC motor driving device such as a linear DC motor, and more particularly to a DC motor driving device using a Hall effect element and a pulse modulator.

[0002]

BACKGROUND OF THE INVENTION Figure 2 shows a DC motor driving device, such as a conventional linear direct current motor, 1 denotes an input terminal to which a torque command signal ± V _T is applied, 2 a to 2 c is the command from the input terminal 1 respectively The Hall effect elements 3a to 3c having input terminals to be applied are pulse width modulations for modulating the output signals from the output terminals of the Hall effect elements 2a to 2c into pulse signals having a pulse width corresponding to the value of the torque command signal. (PWM), 4a to 4c are pulse width modulators 3a, respectively.
A power amplifier for amplifying the pulse width modulated signal from
Reference numerals 5a to 5c are excitation coils, for example, stator coils of the DC motor that are excited by the amplified pulse width modulation signal.

Further, 6a to 6c are absolute value circuits arranged in front of the pulse width modulators 3a to 3c, respectively, for extracting absolute values of outputs of the Hall effect elements 2a to 2c, and 7a to 7c. Direction switching circuits arranged at the subsequent stages of the pulse width modulators 3a to 3c for switching the directions of the pulse signals applied to the power amplifiers 4a to 4c, respectively.
Reference numerals 8a to 8c are polarity discriminating circuits for discriminating the polarities of the outputs of the Hall effect elements 2a to 2c and switching the direction switching circuits 7a to 7c according to the discrimination result.

In this type of conventional DC motor drive device, the Hall effect elements 2a to 2c are fixed to predetermined positions of the stator, and the torque command signal is applied to the output terminal only when the rotor magnetic poles approach each other. The pulse width modulators 3a to 3c generate pulsed signals, which are pulsed. The pulse signals sequentially excite the exciting coils 5a to 5c of the DC motor to rotate the DC motor. ..

[0005]

According to the above-mentioned conventional DC motor drive device, the currents amplified by the power amplifiers 4a to 4c are intermittent according to the pulse width. Compared with the advantage that the heat generation of the power amplifier is reduced and the efficiency is improved, the number of pulse width modulators 3a to 3c corresponding to the number of exciting coils is necessary, and the absolute value circuit and the direction determination associated with this are required. Since many circuits and direction switching circuits are required, the device is complicated and large in size.

The present invention is designed to eliminate the above drawbacks.

[0007]

DISCLOSURE OF THE INVENTION A direct current motor drive apparatus of the present invention includes a pulse modulator for modulating a torque command signal into pulses corresponding to the torque command signal, and each exciting coil to which a pulse signal from the pulse modulator is added. It is characterized by including each corresponding Hall effect element and each power amplifier for amplifying the output of each Hall effect element and applying it to each exciting coil.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

In the present invention, as shown in FIG. 1, ± V _T
Torque command signal from the input terminal 1 to the pulse width modulator 3 via the absolute value circuit 6, and the pulse output from the pulse width modulator 3 via the direction switcher 7 to each exciting coil 5a.
In addition to the Hall effect elements 2a to 2c corresponding to 5c to 5c, the outputs of the Hall effect elements 2a to 2c are applied to the power amplifiers 4a to 4c corresponding to the exciting coils 5a to 5c, respectively, and the input terminal 1 The polarity determination circuit 8 determines the polarity of the torque command signal to be applied to the direction switching circuit 7 according to the determination result.

[0010]

Since the DC motor drive device of the present invention has the above-mentioned configuration, the number of the pulse width modulator and the associated absolute value circuit, polarity discriminating circuit, and direction switching circuit are each one. Therefore, the structure of the device is simplified, and there is a great advantage that it can be made compact.

The present invention can be similarly applied to a DC motor driving device of pulse amplitude modulation, pulse phase modulation, pulse frequency modulation, or the like.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a DC motor drive device of the present invention.

FIG. 2 is a circuit diagram of a conventional DC motor drive device.

[Explanation of symbols]

 1 Input Terminal 2a Hall Effect Element 2b Hall Effect Element 2c Hall Effect Element 3a Pulse Width Modulator 3b Pulse Width Modulator 3c Pulse Width Modulator 4a Power Amplifier 4b Power Amplifier 4c Power Amplifier 5a Excitation Coil 5b Excitation Coil 5c Excitation Coil 6a Absolute Value circuit 6b Absolute value circuit 6c Absolute value circuit 7a Direction switching circuit 7b Direction switching circuit 7c Direction switching circuit 8a Polarity determination circuit 8b Polarity determination circuit 8c Polarity determination circuit

Claims (1)

[Claims] 1. A pulse modulator for modulating a torque command signal into pulses corresponding thereto, Hall effect elements corresponding to respective exciting coils to which a pulse signal from the pulse modulator is added, and Hall effects. A direct-current motor drive device, comprising: each power amplifier for amplifying the output of the element and applying it to each of the exciting coils.