JPH069395U - Motor drive circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a motor drive circuit that can quickly stop the rotation of a motor due to fluctuations in power supply voltage. It is another object of the present invention to provide a motor drive circuit which has a small number of circuit components and saves space. A motor drive circuit for inputting a motor drive signal to rotationally drive the motor, wherein a bridge circuit 105 for rotating the motor by switching the direction of a current flowing through a motor coil and a bridge for inputting the motor drive signal. A logic circuit 104 that outputs a signal to the circuit 105;
A switching circuit 120 interposed between 1 and the logical value circuit 104 to turn on / off the current supply from the power supply 101;
And a circuit that controls the switching circuit 120 in accordance with a change in the output voltage of the power supply 101.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a motor drive circuit for driving a brushless DC motor or the like using two power sources.

[0002]

[Prior art]

 FIG. 4 shows the configuration of a motor stop circuit of a conventional motor drive circuit that drives a brushless DC motor using two power sources. As shown in FIG. 4, the relay circuit 402 is connected between the coil terminals of the motor 107, and the relay circuit 402 is operated by the power supply voltage output from the power supply 401 to be connected to the contact b side. When the output of the motor 107 decreases, the relay circuit 402 is configured to reversely connect to the contact a side so that the coil terminals of the motor 107 are short-circuited and the rotation of the motor 107 is stopped.

[0003]

[Problems to be solved by the device]

 However, in the configuration of the conventional example described above, even if the power supply voltage fluctuates, the time required for the relay circuit 402 to decrease to the voltage at which the relay circuit 402 operates in reverse due to the capacitor component of the motor drive circuit connected to the power supply increases. However, there is a problem that the motor 107 cannot be stopped immediately when the power supply voltage changes. In addition, a space for mounting such relay circuit 402 is required, which is a major obstacle in downsizing the device.

The present invention has been made in view of the above conventional example, and an object of the present invention is to provide a motor drive circuit capable of quickly detecting a variation in a power supply voltage and stopping the rotation of a motor.

Another object of the present invention is to provide a motor drive circuit that realizes space saving with a small number of circuit components.

[0006]

[Means for Solving the Problems]

 In order to achieve the above object, the motor drive circuit of the present invention has the following configuration. That is, a motor drive signal generator that outputs a motor drive signal, a bridge circuit that is connected to a two-system power supply, and that rotates the motor by switching the direction of the current flowing in the motor coil, and the motor drive signal. It is interposed between a logic circuit that inputs and outputs a current direction switching control signal to the bridge circuit and a power supply of two systems and the logical value circuit. Switching means for turning on / off the current supply of the motor, the bridge circuit short-circuits the motor coil with the output of the logic circuit whose current supply is turned off.

[0007]

[Action]

 In the above configuration, the output of the switch means is turned off according to the change of the output voltage of the power supply, thereby turning off the power supply to the logical value circuit. As a result, the motor coil terminals of the output bridge are short-circuited and the motor rotation is stopped.

[0008]

【Example】

 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the functional arrangement of the motor drive circuit of this embodiment.

In FIG. 1, 101 and 102 are power supply circuits, and the power supply 101 supplies power to the logic IC 104 via the output bridge 105 of the drive circuit 110, the motor drive signal generation unit 103 and the switch circuit 106. The power supply 102 similarly supplies power to the output bridge 105 and also provides a reference voltage in the switch circuit 106. 107 is a DC brushless motor.

Next, the configuration of the drive circuit 110 will be described. A motor drive signal generator 103 outputs a signal for rotationally driving the motor 107. Reference numeral 104 denotes a logic IC, which receives power supplied from the source output of the switch circuit 106 and drives each FET of the output bridge 105 based on the signal from the motor drive signal generation unit 103. Reference numeral 105 denotes an output bridge shown in detail in FIG. 3, which inputs six signals from the logic IC 104 and switches the conduction states of the FETs 31 and 32 (FIG. 3) according to the signals, thereby making the coil of the motor 107. An electric current is applied to drive the motor 107 to rotate.

In FIG. 3, reference numeral 31 is a P-channel type FET (field effect transistor), and 32 is an N-channel type FET. Reference numerals 33 to 38 denote signal lines input from the logic IC 104 to the gates of the FETs, and reference numerals 41, 42 and 43 denote signal terminals connected to the coil terminals of the motor 107.

FIG. 2 is a diagram more specifically showing the configuration of the motor drive circuit of the present embodiment shown in FIG. 1. The parts common to FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

The switch circuit 106 includes an N-channel FET 120 and two resistors R1 and R2 that divide the voltage from the power source 102. The voltage signal divided by these resistors R1 and R2 is the FET 120. Has been entered into the gate. On the other hand, the voltage of the power supply 101 is input to the drain of the FET, and the source of the FET 120 is connected to the power supply terminal of the logic IC 104.

With the above configuration, when the output voltage of the power supply 102 drops, the gate voltage of the FET 120 drops, and the FET 120 is turned off. As a result, the power from the power supply 101 is not supplied to the logic IC 104. In this way, all the output signals of the logic IC 104 become low level, and in the output bridge 105, all the FETs 32 are turned off and all the FETs 31 are turned on, so that the coil terminals of the motor 107 are short-circuited and the rotation of the motor 107 is reduced. Will be braked. It is easily understood that when the output voltage of the power supply 101 is reduced, the voltage is not applied to the FET 120, and the power is not supplied to the logic IC 104.

As described above, according to the present embodiment, a circuit having a simple configuration including one small FET and two resistors is used to drive the motor coil when one of the two system power supply voltages drops. It can be short-circuited and braked to stop. In addition, such components are cheaper than conventional relays and can be implemented with a small circuit, so they can be implemented in a small space.

[0017]

[Effect of device]

 As described above, according to the present invention, there is an effect that the rotation of the motor can be quickly stopped due to the fluctuation of the power supply voltage.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing a functional configuration of a motor drive circuit of this embodiment.

FIG. 2 is a block diagram showing a specific circuit configuration of a motor drive circuit of this embodiment.

FIG. 3 is a diagram showing a circuit configuration of an output bridge according to an embodiment.

FIG. 4 is a circuit diagram showing a configuration of a motor stop circuit in a conventional motor drive circuit.

[Explanation of symbols]

 31, 32, 120 FETs 101, 102 Power supply 103 Motor drive signal generation unit 104 Logic IC 105 Output bridge 106 Switch circuit 107 DC brassless motor

Claims (1)

[Scope of utility model registration request] 1. A motor drive signal generator that outputs a motor drive signal, a bridge circuit that is connected to a two-system power supply and that switches the direction of current flowing through a motor coil to drive the motor in rotation. Input to the bridge circuit and outputting a current direction switching control signal to the bridge circuit, and interposed between the two-system power supply and the logical value circuit, and detects a change in the voltage of the power supply to the logic circuit. And a switching means for turning on / off the current supply of the motor circuit, wherein the bridge circuit short-circuits the motor coil with the output of the logic circuit whose current supply is turned off.