JPH04317583A - motor drive device - Google Patents

Abstract

PURPOSE:To delete a fuse element in a simple structure by detecting a state that an output of a switching power source is short-circuited to a ground potential thereby to turn OFF a switching transistor. CONSTITUTION:If a state such as a short-circuit of a smoothing capacitor or a short-circuit accident of a connector or a wire material to a ground potential occurs and an output of a switching power source 7 becomes lower than a voltage value of a DC power source 13, an output of a compactor 5 becomes an 'L' potential, thereby turning ON a P-N-P transistor 30b through a resistor 30. Since a DC power source 12 of a voltage higher than a triangular wave signal is connected to an emitter terminal of the transistor 30b, a plus terminal of the comparator 5 becomes a voltage higher than the signal input to a minus terminal. Thus, the output of the comparator 5 is turned OFF, i.e., the power source 7 is turned OFF thereby to prevent an excess current from flowing from the power source 7. Thus, a fuse element can be deleted.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive device that can be used as a drive source for various video equipment, audio equipment, etc.

0002

[Prior Art] In recent years, a DC brushless motor drive device configured to sequentially switch the current flowing to a plurality of armature coils using semiconductor elements such as transistors using a Hall element or an induced voltage in an armature coil has been developed. It is widely used as a drive source for equipment and audio equipment.

An example of the above-mentioned motor drive device will be explained below with reference to the drawings. FIG. 2 is a circuit configuration diagram of a main part of a conventional three-phase full-wave type motor drive device that drives a three-phase brushless motor using a Hall element. In FIG. 2, 1a, 1b, and 1c are armature coils, and 1g is a rotor magnet. 1d, 1e, and 1f are Hall elements disposed on the stator, and 10 is a DC power supply that supplies voltage to the Hall elements. Reference numeral 2 denotes a position signal synthesis circuit for controlling energization from each differential output of the Hall elements 1d, 1e, and 1f to the armature coil, and includes PNP type transistors 3a, 3.
The base currents of the transistors b, 3c and the NPN transistors 3d, 3e, and 3f are controlled. The output transistor is
PNP type and NPN type collector terminals are connected to each phase, and the rotor magnet 1g is driven by sequentially supplying and attracting current to the armature coil of each phase. 9 is a resistor that converts all the current flowing through the motor into voltage. 4 is an error for controlling the magnitude of the output current of the position signal synthesis circuit by detecting the difference between the torque command voltage ET that controls the rotational speed of the motor and the generated torque and the voltage generated in the resistor 9; It's an amplifier.

[0004] Even in conventional motor drive devices, cylinder motors and capstan motors such as camera-integrated VTRs that use primary batteries or secondary batteries as the power source of the device, in order to reduce power consumption in the motor drive device. A switching power supply is used. The operation will be explained below using FIGS. 2 and 3. 7 is a switching transistor 7a, a clamp diode 7b, a smoothing coil 7c, and a capacitor 7d.
This is a switching power supply unit consisting of a switching power supply section, the output of which is connected to the common emitter terminal of the PNP transistor. A triangular wave generating circuit 20 generates a triangular wave signal, and the signal is connected to the negative terminal of the comparator 5. 6 detects the maximum value of the voltage induced in the armature coils of the three phases, and detects the difference voltage between that voltage and the output voltage of the switching power supply circuit, that is, between the emitter and collector of the PNP transistor of each phase. This is a voltage detection circuit that detects voltage. The output of the voltage detection circuit is connected to the positive terminal of the comparator 5 via a filter circuit 8 composed of a resistor 8a and a capacitor 8b. The output of the comparator 5 is connected to the base terminal of the switching transistor 7a. FIG. 3 is an input/output characteristic diagram of the voltage detection circuit 6. A voltage Va is output in proportion to the emitter-collector voltage of the PNP transistor, and this voltage Va is compared with a triangular wave signal Vb having a DC bias to control the on/off duty of the DC power supply 11 using the switching transistor 7a. By doing this, the voltage can be varied according to the motor load torque and rotation speed. As can be seen from Figure 3, PNP
The emitter-collector voltage of the type transistor is controlled between V1 and V2. Note that the filter circuit 8 is normally inserted in order to reduce the ripple voltage of the output of the switching power supply.

Reference numeral 21 denotes a fuse element, which can be used to prevent short-circuiting of the smoothing capacitor 7d in the switching power supply shown in 7, or because the switching power supply unit 7 and the motor drive unit are normally located at separate locations inside the device, so it is necessary to use a connector or a connector to connect them. It is connected between the DC power supply 11 and the emitter terminal of the switching transistor 7a in case of an abnormality such as a short-circuit accident between the wire and the ground potential.

[0006]

[Problem to be Solved by the Invention] However, in the case of the fuse element shown in FIG. 2, which is a normal fuse, there is a large variation in the value of the current that blows, and when the DC resistance value of the smoothing coil and the on-resistance value of the switching transistor are taken into consideration. Since there is a possibility that the fuse will not blow, an expensive semiconductor fuse is used, although the variation in current value is small. In addition, it is generally difficult to miniaturize fuse elements, so it is difficult to miniaturize fuse elements, so
In devices such as R that require miniaturization, there has been a problem in that this is a factor that inhibits miniaturization and high-density packaging.

In view of the above problems, the present invention provides means for eliminating the fuse element with a simple configuration.

[0008]

[Means for Solving the Problems] In order to solve the above problems, a motor drive device of the present invention includes a position signal synthesis circuit that synthesizes energization signals to a plurality of armature coils arranged on a stator; A plurality of PNP type transistors and an NPN type transistor whose energization is controlled by the output of the position signal synthesis circuit, and a collector of the plurality of PNP type transistors.
A voltage detection circuit that detects the voltage between the emitters, a triangular wave generation circuit that generates a triangular wave signal, a comparator that compares the output of the voltage detection path and the triangular wave signal, and is controlled on/off by the output of the comparator. This includes a switching power supply circuit and a comparison circuit that receives the output of the switching power supply circuit and a first voltage source and turns off the switching power supply only when the output voltage of the switching power supply is lower than the voltage of the first voltage source. .

[0009]

[Operation] With the above-described configuration, the present invention detects the state in which the output of the switching power supply is short-circuited to the ground potential and turns off the switching transistor, thereby preventing excessive current from the power supply and eliminating the need for a fuse element. It will be possible.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS A motor drive device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram of a main part of a three-phase brushless motor drive device according to an embodiment of the present invention. In Fig. 1, 1 is armature coil 1a
, 1b, 1c Hall elements 1d, 1e, 1f and a rotor magnet are three-phase brushless motors. 2 is a position signal synthesis circuit, 3 is an output stage transistor, 4 is an error amplifier, 6 is a voltage detection circuit, 8 is a filter circuit, 20 is a triangular wave generation circuit, 5 is a comparator, and 7 is a switching power supply circuit, which is a DC voltage source. 11 is directly connected to the emitter terminal of the switching transistor 7a. The above configuration is the same as the conventional motor drive device except for the fuse element 21. A DC voltage source 13 is connected to the negative terminal of the comparator 30, and its voltage value is set lower than the lower limit voltage of the switching power supply output voltage at which the motor drive device operates. The output of the switching power supply is input to the positive terminal of the comparator 30. 30b is PN
The P-type transistor has its collector terminal connected to the output of the voltage detection circuit 6, and its base terminal connected to the output of the comparator 30 via a resistor 30. The emitter terminal of 30b is connected to the DC power supply 12. The voltage value of the DC power supply 12 is set to a voltage larger than the maximum value of the output voltage of the triangular wave generation circuit. 30c is a relatively high resistance resistor connected between the output of the switching power supply 7 and the DC power supply 12.

The operation of the motor drive device configured as described above will be explained below with reference to the drawings.

The operations of the position signal synthesis circuit 20, output stage transistor, and error amplifier 4 in FIG. 1 are the same as those of the conventional motor drive device described above. Further, when the present motor drive device is operating normally, the operations of the voltage detection circuit 6, comparator 5, and switching power supply 7 are the same as in the conventional motor drive device described above. If a situation such as a short circuit in a smoothing capacitor or a short circuit accident with a connector or wire with the ground potential occurs and the output of the switching power supply 7 becomes lower than the voltage value of the DC power supply 13, the output of the comparator 30 becomes 'L'. It becomes a potential and turns on the PNP type transistor 30b via the resistor 30. Since the DC power supply 12 with a higher voltage than the triangular wave signal is connected to the emitter terminal of 30b, the positive terminal of the comparator 5 has a higher voltage than the triangular wave signal input to the negative terminal. 5 is turned off, that is, the switching power supply 7 is turned off, and excessive current can be prevented from flowing from the switching power supply 7.

In normal operation, the output voltage of the switching power supply 7 is applied to the output stage transistors 3a, 3b, 3c and 3.
It operates to ensure the emitter-collector voltages of d, 3e, and 3f and the voltages induced in the armature coils 1a, 1b, and 1c. Since the voltage of the DC power supply 13 is set lower than the lower limit of the switching power supply output voltage at which this motor drive device operates (i.e., the voltage of V1 shown in FIG. 3 above), the output voltage of the switching power supply 7 is , does not become lower than the DC power supply 13, and therefore the PNP transistor 30a remains in the off state, so there is no problem during normal operation. Further, the resistor 30c is connected to prevent the positive terminal of the comparator 30 from becoming lower than the voltage of the DC power supply 13 when the motor drive device is stopped, and to ensure reliable startup of the switching power supply 7 at the time of startup. are doing. As is clear from FIG. 1, the present invention can be realized with a relatively simple circuit configuration, can be easily realized even when configured on the same integrated circuit, and is extremely useful in practice. Further, the embodiments of the present invention are not limited to the above-described embodiments, and can be modified to a certain extent without changing the spirit of the present invention.

[0014]

[Effects of the Invention] As described above, according to the motor drive device of the present invention, it is possible to prevent excessive current due to an output short circuit of a switching power supply with a relatively simple configuration, and it is possible to eliminate fuse elements that were conventionally required. Excellent effects can be obtained.

[Brief explanation of drawings]

[Fig. 1] Main part circuit diagram of a motor drive device according to an embodiment of the present invention.

[Figure 2] Main part circuit diagram of a conventional motor drive device

[Figure 3] Input/output characteristic diagram in one embodiment of the present invention

[Explanation of symbols]

1a Armature coil 1b Armature coil 1c Armature coil 1d Hall element 1e Hall element 1f Hall element 1g rotor magnet 2 Position signal synthesis circuit 3 Transistor 4 Error amplifier 5 Comparator 6 Voltage detection circuit 7 Switching power supply circuit 10 DC power supply 11 DC power supply 12 DC power supply 13 DC power supply 30 Comparator

Claims (2)

[Claims] 1. A position signal synthesis circuit that synthesizes energization signals to a plurality of armature coils arranged on a stator, a plurality of PNP type transistors whose energization is controlled by the output of the position signal synthesis circuit, and Comparing an NPN transistor, a voltage detection circuit that detects the voltage between the collector and emitter of the plurality of PNP transistors, a triangular wave generation circuit that generates a triangular wave signal, and an output of the voltage detection circuit and the triangular wave signal. a switching power supply circuit whose on/off is controlled by the output of the comparator; an output of the switching power supply circuit and a first voltage source are input, and the output power of the switching power supply circuit is controlled to be on/off by the output of the switching power supply circuit; A motor drive device comprising a comparison circuit that turns off the switching power supply only when the voltage is lower than the voltage of the power source. 2. The motor drive device according to claim 1, wherein the first voltage source is set lower than a lower limit voltage for operation of the motor drive device.