JPH05168282A - Driver for motor - Google Patents

Abstract

PURPOSE:To obtain a driver for a motor adapted for driving the motor having a large series resistance component or when a power source voltage is low. CONSTITUTION:A current proportional to a winding current flowing in a winding of a motor is Miller-amplified by output transistors 12-14 and current-Miller- coupled sensor transistors 18-20, fed to a current detecting resistor 6, and a current detection voltage is generated. This voltage is fed back to a comparator 1, compared by an input voltage and so regulated that both become the same. Thus, a current responsive to the input voltage flows to windings 9-11, and a voltage higher a level corresponding to a current detection voltage can be applied to the winding by inserting the resistor 6 for detecting the current not in series with the windings 9-11 but to another section in the circuit.

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 suitable for driving a motor driven with a low power supply voltage, a motor having a large resistance component, and the like.

[0002]

2. Description of the Related Art In recent years, in order to control the number of rotations of a motor and to improve load characteristics, a motor drive device has been used in which a voltage according to a required torque is applied, converted into a current and supplied to the motor. It's coming.

A conventional motor drive device will be described below. In a conventional brushless DC motor, current is applied in both directions to a three-phase coil connected in a star shape (full-wave drive) to improve the utilization efficiency of the coil. In this method, a constant current is supplied to the multiphase coil by the first transistor group, and the potential of the common connection point of the multiphase coil is controlled to be a predetermined value by the second transistor group. (See Japanese Examined Patent Publication No. 55-6938).

FIG. 3 is a circuit diagram of a conventional motor drive device. 1 is a comparator, 2 is an energization switching circuit, 6 is a current detection resistor, 7 is a power supply voltage terminal, 8 is a torque command input terminal, and 9-.
Reference numeral 11 is a motor winding (hereinafter abbreviated as a winding), 12 to 14 are output transistors of a driving device, and 15 to 17 are output transistors having polarities opposite to those of the output transistors 12 to 14 (hereinafter referred to as reverse polarity output transistors). 21 to 26 are transistors forming the energization switching circuit 2, 27 is a midpoint control circuit, 28 to 32 are resistors forming the midpoint control circuit 27,
33 to 35 are transistors forming the midpoint control circuit 27, 36 is a resistance common connection point in which the resistors 31 and 32 are commonly connected, 37 is a winding common connection point in which the windings 9 to 11 are commonly connected, 38 is an energization switching circuit 2 according to the output of the comparator 1.
Transistors for energizing the transistors 24 to 26 of 3
9 is a resistance.

The operation of the conventional motor drive device constructed as described above will be described below. First, a voltage corresponding to the current to be passed through the motor is input from the torque command input terminal 8 to set the voltage at the non-inverting input end of the comparator 1. Next, the output of the comparator 1 is converted from a voltage to a current by the transistor 38 and supplied to the transistors 24 to 26 that form the energization switching circuit 2. Transistor 2
4 to 26 have their bases switched by a signal from a position detecting means such as a Hall element (not shown) for detecting the motor position, and drive the reverse polarity output transistors 15 to 17. The reverse polarity output transistors 15 to 17 are
Currents flowing through the windings 9 to 11 (winding currents I _U , _IV , I _W )
Sequentially switch. When a current flows through the windings 9 to 11, the potential at the common winding connection point 37 rises. When this potential is input to the midpoint control circuit 27 and becomes higher than the preset potential by the resistors 31 and 32 in the midpoint control circuit 27, a current flows through the transistors 21 to 23 of the energization switching circuit 2 and the output transistor 12 To 14 are driven, a current flows through the windings 9 to 11, the potential of the winding common connection point 37 decreases, and the potential becomes substantially the same as that of the resistance common connection point 36. Winding 9
The current flowing to 11 flows to the current detection resistor 6. This current I _RCS is a combined current obtained by adding the winding currents I _U , I _V , and I _W. The current detection resistor 6 generates a current detection voltage according to the current I _RCS and negatively feeds back the current detection voltage to the comparator 1. The comparator 1 compares the input voltage and the current detection voltage so that the two become the same so that the reverse polarity output transistors 15 to 1 are provided.
7 and consequently also the output transistors 12-14 through the midpoint control circuit 27. By this,
A current corresponding to the input voltage of the torque command flows through the windings 9 to 11.

[0006]

However, in the above-mentioned conventional configuration, since there is a current detection voltage generated in the current detection resistor 6, if the power supply voltage is constant, an effective load voltage that can be used in the windings 9 to 11 is obtained. Had a problem in that it was damaged by the current detection voltage generated in the current detection resistor 6. This means that as the size of portable magnetic playback devices (headphone stereos, etc.) and floppy disk devices becomes smaller and the voltage becomes lower, the winding becomes thinner and the motor becomes smaller. Will occur.

Further, the current detection resistor 6 is usually as small as about 1 Ω, and high precision is required. The wiring resistance component of the wiring pattern at the time of mounting on the substrate cannot be ignored, and there is a restriction that it must be connected by thick and short wiring. there were. In addition, when the resistance value of the current detection resistor 6 is too small and is configured in the semiconductor integrated circuit, there is a problem that the area of the resistor becomes large and the integration degree of the semiconductor integrated circuit is reduced.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a motor drive device suitable for a motor having a low power supply voltage and a large resistance component.

[0009]

In order to achieve this object, a motor drive device according to the present invention has a structure in which one end is commonly connected.
Phase windings and n with collectors respectively connected to the other ends of the windings
Output transistors, n sensor transistors that are current-mirror coupled to each output transistor, a resistor connected to the common connection point of the collectors of each sensor transistor, the voltage across this resistor, and a torque command signal. And a comparator for outputting an error signal and switching the error signal for each phase according to the change of the rotating magnetic field of the motor, and energization switching for making n output transistors conductive according to the switched error signal. The circuit includes a circuit and a midpoint control circuit that controls a common connection point of the windings to a set voltage.

[0010]

With this configuration, the current detection resistor for detecting the current in the winding can be inserted in the collector circuit of the sensor transistor mirror-coupled with the output transistor for driving the current in the winding. Since it does not limit the voltage applied to the winding, a higher voltage can be applied to the winding. Therefore, if the winding resistance is the same, a large amount of current can be passed, so that the torque of the motor can be increased, and conversely, the winding can be thinned to downsize the motor.

Further, if the mirror ratio between the output transistor and the sensor transistor is increased, the current flowing through the current detection resistor can be decreased, and the accuracy is deteriorated due to the resistance component of the wiring pattern at the time of board mounting and the contact resistance with the semiconductor integrated circuit. Can be prevented. Further, since the current detection resistor can have a resistance value of several hundreds Ω to several KΩ, it becomes easy to incorporate the current detection resistor in the semiconductor integrated circuit.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a motor drive device according to an embodiment of the present invention, showing a motor drive device for driving a three-phase full-wave motor. In FIG. 1, 1
Is a comparator, 2 is an energization switching circuit, 6 is a current detection resistor that generates a voltage drop corresponding to the current of the winding, 7 is a power supply voltage terminal, 8 is a torque command input terminal, 9-11 are windings, and 12-
14 is an output transistor, 15 to 17 are reverse polarity output transistors, 18 to 20 are sensor transistors in which the base and emitter are commonly connected to the base and emitter of the output transistors 12 to 14, and 21 to 26 are energization switching circuits. 2 is a transistor, 27 is a midpoint control circuit, 28 to 32 are resistors that constitute the midpoint control circuit 27,
33 to 35 are transistors forming the midpoint control circuit 27, 36 is a resistance common connection point that commonly connects the resistors 31 and 32, and 37 is a winding common connection point that commonly connects the windings 9 to 11 , 38 are transistors that energize the transistors 24 to 26 of the energization switching circuit 2 by the output of the comparator 1.

A set voltage corresponding to a desired current flowing through the winding is applied from the torque command input terminal 8 to the inverting input terminal of the comparator 1, and the current detecting resistor 6 is applied to the non-inverting input terminal of the comparator 1.
The voltage drop generated in 1 is given, and the comparator 1 amplifies the difference voltage and outputs it as an error signal. Transistor 3
Reference numeral 8 converts the output of the comparator 1 from a voltage to a current and supplies the current to the transistors 24 to 26 forming the energization switching circuit 2.
The bases of the transistors 21 to 26 constituting the energization switching circuit 2 are switched by a signal from a position detecting means such as a Hall element for detecting the motor position, and the output transistors 12 to 14 and the reverse polarity output transistors 15 to 17 are switched.
To drive. The output transistors 12 to 14 and the reverse polarity output transistors 15 to 17 have windings 9 to the collectors, respectively.
11 is connected, and the output signal of the energization switching circuit 2 sequentially conducts at every energizing angle of 120 degrees. The sensor transistors 18 to 20 have their bases and emitters commonly connected to the bases and emitters of the output transistors 12 to 14, respectively, and conduct with the collector currents of the output transistors 12 to 14 at a predetermined ratio. The current detection resistor 6 is connected to the common connection point of the commonly connected collectors.

As described above, in the motor drive device of this embodiment, the comparator 1, the energization switching circuit 2, the sensor transistors 18 to 20 and the current detection resistor 6 form a feedback loop, and the windings 9 to 11 are connected. A voltage drop corresponding to the flowing current is generated between the terminals of the current detection resistor 6, and the voltage between the terminals is input to the non-inverting input terminal of the comparator 1 and negatively fed back.

The operation of the motor drive device of this embodiment having the above-described structure will be described below with reference to the signal waveform diagram shown in FIG. First, a voltage corresponding to the current desired to flow to the motor is input from the torque command input terminal 8 to set the voltage at the inverting input end of the comparator 1. The signals H _U , H _V , and H _W from the Hall elements are appropriately processed and input to the energization switching circuit 2, and the output of the comparator 1 is switched according to the signals to drive the bases of the transistors 24 to 26. Input signals U _U , V _U and W _U.

Transistors 24-26 have windings 9-11.
The winding currents I _U , I _V , and I _W are sequentially switched to flow. When the transistors 24 to 26 start to energize, the winding common connection point 3
The potential of 7 rises. Along with this, the midpoint control circuit 27 supplies a current to the transistor 33 so that the potential is set at the common resistance connection point 36, and the transistors 21 to 23 of the energization switching circuit 2 supply the current to the hall signal H _U ,
The output transistor 12 to be switched depending on H _V and H _W
The drive signals U _d , V _d , and W _d are input to the base of 14.

The output transistors 12-14 are windings 9-1.
Winding current I to 1_U, I_V, I_W Apply the same amount of current as the
The potential of the common connection point 37 is lowered. These currents are
A sensor in which the current transistors 12 to 14 are coupled to the current mirror.
Current of a constant ratio K times by the transistors 18 to 20
And flows into the current detection resistor 6. That is, the winding current I _U
Current flows through the current detection resistor 6 by a factor of K_UFlow
And K times I as well_V, K times I_WFlows. This current I
_RCSIs the winding current I_U, I_V, I_W K times the synthesized one
Becomes The current detection resistor 6 has a current I_RCS Current detection according to
Generate a voltage and feed back the current detection voltage to the comparator 1.
It The comparator 1 compares the input voltage with the current detection voltage and
Reverse polarity output transistors 15 to 1
7 to drive the output transistor by the midpoint control circuit 27.
Drive 12 to 14. Therefore, input the torque command
A current corresponding to the pressure flows through the windings 9 to 11.

As described above, according to this embodiment, the windings 9 to 11 of the three-phase full-wave motor are sequentially energized with a conduction angle of 120 degrees to make the driving current uniform among the three-phase windings. In addition, since the current detection is performed by using the current detection resistor 6 of the collector circuit of the sensor transistors 18 to 20 provided in parallel with the output transistors 12 to 14, the current paths of the windings 9 to 11 are determined. Is a series circuit of only the windings 9 to 11 and the output transistors 12 to 14 so that the ratio of the voltage applied to the windings 9 to 11 to the power supply voltage can be increased, and the three-phase full-wave motor operating at a low power supply voltage. A drive device can be realized.

In this embodiment, the sensor transistors 18 to 20 are combined with the NPN output transistors 12 to 14, but the PNP reverse polarity output transistors 15 to 14 are connected.
17 and a current mirror may be coupled. Further, all the transistors may be bipolar type or MOS type.

[0020]

As described above, according to the present invention, the windings of the n-phase motor are sequentially energized, the driving current can be made uniform among the n-phase windings, and the sensor is provided in parallel with the output transistor. Since current detection is performed using the current detection resistor of the collector circuit of the transistor for use, the current path of the winding is a series circuit consisting only of the winding and the output transistor, and the ratio of the voltage applied to the winding to the power supply voltage must be increased. Can
An n-phase motor drive device that operates with a low power supply voltage can be realized.

Further, if the power source utilization efficiency can be improved in this way, the motor can be miniaturized by thinning the winding when driven by the same power source voltage as the conventional one, and the same resistance value as the conventional one can be obtained. When driving the winding, it is possible to increase the torque of the motor as much as a large current can flow.

When a current detection resistor is provided in the current path of the winding as in the conventional example, the resistance value of the current detection resistor is 1Ω.
In the present invention, the current detection resistance can be set to a resistance value of several hundred Ω to several KΩ by increasing the mirror ratio between the output transistor and the sensor transistor. It becomes easy to build a current detection resistor inside. Further, in the conventional example, the external terminal of the semiconductor integrated circuit device for connecting the current detection resistor was required, but in the present invention, it is not necessary to particularly provide the external terminal for the current detection resistor, and one external terminal can be reduced. Therefore, it is possible to reduce the size of the semiconductor integrated circuit incorporating the motor drive device and reduce the number of external parts.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a three-phase full-wave motor drive device according to an embodiment of the present invention.

FIG. 2 is a signal waveform diagram of the same three-phase full-wave motor drive device.

FIG. 3 is a circuit diagram of a conventional three-phase full-wave motor drive device.

[Explanation of symbols]

 1 Comparator 2 Energization Switching Circuit 6 Current Detection Resistance (Resistance) 9, 10, 11 Winding (Motor Winding) 12, 13, 14 Output Transistor 18, 19, 20 Sensor Transistor 27 Midpoint Control Circuit 37 Winding Common connection point (the point where the windings are commonly connected)

Claims (1)

[Claims] 1. An n-phase (n is an integer of 2 or more) phase motor winding having one end commonly connected, and n output transistors each having a collector connected to the other end of the motor winding.
N sensor transistors that are current-mirror-coupled to each output transistor, and resistors connected to a point where the collectors of the sensor transistors are commonly connected.
A comparator that compares the terminal voltage of the resistor with a torque command signal and outputs an error signal, and switches the error signal for each phase according to the change of the rotating magnetic field of the motor magnet, and to the switched error signal. Accordingly, the motor drive device includes an energization switching circuit that electrically connects the n output transistors, and a midpoint control circuit that controls a point where the motor windings are commonly connected to a set voltage.