JP2645907B2 - Motor drive circuit - Google Patents

Description

The present invention relates to a motor drive circuit.

(B) Conventional technology FIG. 3 is a main part circuit diagram showing a conventional motor drive circuit.

In FIG. 3, the drive circuits (1U) (1V) (1W) supply a drive current to the drive coils U, V, W. In the driving circuit (1U) (1V) (1W), the logic signals S _U1 and S
_U2 , _SV1 , _SV2 , _SW1 , _SW2 are "H" (high level) or "L" depending on the state of supplying the drive current to the drive coils U, V, W.
(Low level). In the driving circuit (1U), the driving transistor Q ₁₁ Q ₁₂ are Darlington connected, the logic signal S _U1 is operated by being supplied. Driving transistor Q ₁₃ Q ₁₄ Q ₁₅ are Darlington connected, the logic signal S _U2 is operated by being supplied. The control transistor Q ₁₆ is connected between the base and the ground of the drive transistor Q _13, the driving transistor Q
Controls the operation of the ₁₃ Q ₁₄ Q _15. Drive circuit (1U) (1V)
Since (1W) is the same circuit, the description of the drive circuits (1V) and (1W) is omitted. The detection resistance R _f is determined by the drive transistor Q ₁₅ Q ₂₅ Q ₃₅
, And detects the drive current of the drive transistors Q ₁₂ Q ₁₅ , Q ₂₂ Q ₂₅ , and Q ₃₂ Q ₃₅ . That is, as described later, if the load is applied to prevent rotation of the motor, the terminal voltage V _Rf large next to the detection resistor R _f, also if no load to prevent rotation of the motor, the detection resistor R The terminal voltage _{VRf of f} becomes small.

Comparator circuit (2) is to compare the terminal voltage of the detection resistor R _f V _Rf and reference voltage V _T1, and controls the driving current of the driving transistor Q ₁₅ Q ₂₅ Q _35. In the comparison circuit (2),
The transistor Q ₁ Q ₂ Q ₃ Q ₄ and the current source I _D1 are a differential circuit, and compare the terminal voltage V _Rf of the detection resistor R _f with the reference voltage V _T1 . Transistor Q ₅ Q ₆ is a current mirror circuit, operates in accordance with the collector current of the transistor Q _2. Transistor Q ₇ operates according to the difference current of the collector current of the transistor Q ₄ Q _6. Transistor Q ₈ is connected between the constant voltage V _T2 and ground, and operates in accordance with a difference current between the collector current of the supply current and the transistor Q ₇ of the current source I _D2. That is, the control transistor Q ₁₆ Q ₂₆ Q ₃₆ will operate in accordance with a difference current between the constant current and the collector current of the transistor Q ₈ caused by the constant voltage V _T2. Incidentally, in the normal driving state of the motor, the terminal voltage V _Rf of the detection resistor R _f is assumed to be set to smaller than the reference voltage V _T1.

The drive circuit (1U) (1V) (1W), the detection resistor R _f , and the comparison circuit (2) form a loop for limiting the maximum drive current of the motor, and attempt to protect the motor drive circuit. Things.

For example, if the load is applied to prevent rotation of the motor, the other negative feedback loop (not shown) to operate in accordance with the terminal voltage V _Rf of the detection resistor R _f, the driving transistor Q ₁₂ Q
_15, the drive current of _{Q 22 Q 25, Q 32 Q} 35 is large, and the well terminal voltage V _Rf of the detection resistor R _f becomes larger me not interfere with the rotation of the motor. Therefore, the transistor Q ₁ Q ₂ Q ₃ Q ₄ is in an equilibrium state when the terminal voltage V _Rf of the detection resistor R _f becomes equal to the reference voltage V _T1 , that is, the driving transistors Q ₁₂ Q ₁₅ , Q ₂₂ Q ₂₅ , The maximum drive current of Q ₃₂ Q ₃₅ is that the terminal voltage V _Rf of the detection resistor R _f is the reference voltage V _T1.
And the motor drive circuit is protected.

(C) Problems to be Solved by the Invention However, there is a problem that power consumption is increased due to the method of limiting the maximum drive current of the motor.

Therefore, the present invention can reduce the power consumption by turning off the drive transistor when a load for preventing rotation of the motor is applied, and furthermore, when the drive transistor is turned on and a through current flows, the comparison signal of the comparison circuit is reduced. It is an object of the present invention to provide a motor drive circuit which can invalidate the above.

(D) Means for Solving the Problems The present invention has been made to solve the above problems, and has a detection resistor for detecting a drive current of a drive transistor for driving a motor; And a control transistor that turns off the drive transistor based on the comparison signal of the first comparison circuit. A flip-flop circuit, a set circuit that sets the flip-flop circuit based on a comparison signal of the first comparison circuit, and a control circuit that turns on and off the control transistor based on a set-reset signal of the flip-flop circuit A charge / discharge circuit for charging / discharging a capacitor based on a set / reset signal of the flip-flop circuit; A second comparison circuit that compares a charge / discharge signal by the charge / discharge circuit with a second reference signal, and invalidates the comparison signal of the first comparison circuit based on the comparison signal of the second comparison circuit. A reset circuit that resets the flip-flop circuit based on a comparison signal of the second comparison circuit;
A variable circuit that varies the second reference signal to a first level or a second level based on a comparison signal of the second comparison circuit, wherein the second reference signal is at a first level. During a period in which the first comparison circuit is kept at the second level from the second comparison circuit, the comparison signal of the first comparison circuit is invalidated, and malfunction by the first comparison circuit is prevented.

(E) Function According to the present invention, when a load for preventing the rotation of the motor is applied, the driving transistor is turned off and the power consumption is reduced. Furthermore, when the drive transistor is turned on and a through current flows, the comparison signal of the comparison circuit is invalidated, and malfunction by the comparison circuit is prevented.

(F) Example The details of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a motor drive circuit according to the present invention, which is assumed to be integrated on one chip.
The same elements in FIGS. 1 and 2 are denoted by the same reference numerals.

In FIG. 1, a first comparison circuit (3) includes a detection resistor.
It is to compare the terminal voltage of the R _f V _Rf and reference voltage V _T1. In the normal driving state of the motor, the detection resistance R _f
The terminal voltage V _Rf of shall be set to smaller than the reference voltage V _T1.

The flip-flop circuit (4) is of a set / reset type. In the flip-flop circuit (4), the transistors Q _{42 and} Q ₄₃ are connected in series between the power supply voltage V _CC and the base of the transistor Q ₄₀ , and the flip-flop circuit (4)
Set the initial state of. Transistor Q ₅₉ (set circuit) operates in response to the difference current between the collector current of the supply current and the transistor Q ₇ of the current source I _D2, is to set the flip-flop circuit (4).

The control circuit (5) controls the control transistors Q ₁₆ Q ₂₆ based on the set reset signal of the flip-flop circuit (4).
In which controls the operation of Q _36. In the control circuit (5), the transistor Q ₄₄ is a flip-flop circuit (4)
Are operated when the set-reset signal is supplied. Transistor Q ₄₅ is connected between the constant voltage V _T2 and ground, and operates in accordance with a difference current between the collector current of the supply current and the transistor Q ₄₄ of the current source I _D3. That is, the control transistor Q ₁₆ Q
₂₆ Q ₃₆ is turned off when the set / reset signal of the flip-flop circuit (4) is “H”, and turned on when the set / reset signal of the flip-flop circuit (4) is “L”.

The charge / discharge circuit (6) charges / discharges an externally connected capacitor C based on the set / reset signal of the flip-flop circuit (4). In the charge-discharge circuit (6), the transistor Q ₄₆ operates in accordance with the difference current between the collector current of the supply current and the transistor Q ₄₄ of the current source I _D3. Transistor Q ₄₇ is a constant voltage V _T3 operates is applied. Incidentally, the collector current of the transistor Q ₄₇ is a constant current by the resistor R ₃ which are externally connected. The transistors Q ₄₈ Q ₄₉ Q ₅₀ are current mirror circuits, and operate by the collector current of the transistor Q ₄₇ . Transistors Q ₅₁ Q ₅₂ are current mirror circuits, and transistors Q ₅₁
It operates according to the difference current of the collector current of ₄₈ Q ₅₀ . That is, when the time set-reset signal of the flip-flop circuit (4) is "H", the capacitor C and the transistor Q ₅₂ form a discharge loop, the set-reset signal of the flip-flop circuit (4) is "L", capacitor C and the transistor Q ₄₉ will form a charge loop.

The second comparison circuit (7) calculates the terminal voltage V _{C of the} capacitor _C.
And a reference voltage _VT5 . In the second comparison circuit (7), the transistor Q ₅₃ Q ₅₄ Q ₅₅ Q ₅₆ and the current source _ID5 are a differential circuit, and the terminal voltage V _{C of the} capacitor _C
And the reference voltage _VT5 . Transistors Q ₅₇ Q ₅₈
A current mirror circuit, operates in response to the collector current of the transistor Q _56. Transistor Q ₆₀ operates in accordance with the difference between the current of the collector current of the transistor Q ₅₄ Q _58. That is, the transistor Q ₆₀ does not operate when the larger than the terminal voltage V _C is the reference voltage V _T5 of the capacitor C, so that the terminal voltage V _C of the capacitor C is operated when less than the reference voltage V _T5. Transistor Q ₆₁ (disabled circuit) operates in response to the difference current between the collector current of the supply current and the transistor Q ₆₀ of the current source I _D4, intended to invalidate the comparison result of the first comparator circuit (3) is there. Transistor Q ₆₂ (reset circuit)
Operates in accordance with a difference current between the collector current of the supply current and the transistor Q ₆₀ of the current source I _D4, it is to reset the flip-flop circuit (4).

The variable circuit (8) _changes the reference voltage _VT5 . In the variable circuit (8), the resistance R ₄ R ₅ is a constant voltage V _T4
And connected in series between the ground, the resistor R ₅ is connected between the base and the ground of the transistor Q _55. Transistor Q ₆₃ operates in accordance with a difference current between the collector current of the supply current and the transistor Q ₆₀ of the current source I _D4, the resistor R ₅ R ₆ connected in parallel. That is, the reference voltage V _T5 will vary according to the operating state of the transistor Q _63, it would have a hysteresis. The resistance value of the resistor R ₄ R ₅ R ₆ is set so that the comparison result of the first comparison circuit (3) becomes invalid at least during the period of generation of the through current of the drive circuit (1U) (1V) (1W). Is set.

Hereinafter, the operation of FIG. 1 will be described based on the waveform diagram of FIG.

First, when no load to prevent rotation of the motor, the detection resistor terminal voltage V _Rf of R _f for becomes smaller than the reference voltage V _T1, the set-reset signal of the flip-flop circuit (4) becomes "H", The control transistors Q ₁₆ Q ₂₆ Q ₃₆ are turned off. That is, the drive circuit (1U) (1V) (1W) in FIG.
Operate according to the state of supplying the drive current to the drive coils U, V, W. At this time, since the transistor Q ₅₂ is turned on, the charge of the capacitor C is in the state of being discharged through the transistor Q _52. Therefore, transistor Q ₅₈
Is turned off, the transistor _Q63 is turned off, and the reference voltage V _T5
Is a value V _{T5OFF obtained} by dividing the resistance R ₄ R ₅ .

Then, if the load is applied to prevent rotation of the motor terminal voltage V _Rf of the detection resistor R _f is made large. Then, at time t _0, the detection resistor reference terminal voltage V _Rf of R _f voltage V _T1
Is equal to, the set reset signal of the flip-flop circuit (4) becomes “L”, and the control transistors Q ₁₆ Q ₂₆
Q ₃₆ turns on. That is, the base of the driving transistor Q ₁₃ Q ₂₃ Q ₃₃ is grounded driving circuit (1U) (1V) (1W ) is stopped working, the terminal voltage V _Rf of the detection resistor R _f is zero. At the same time, since the transistor Q ₅₂ is turned off, the charge of the capacitor C begins to be charged through the transistor Q _49. Then, at time t _1, when the terminal voltage V _C of the capacitor C becomes equal to the reference voltage V _T5OFF, since the transistor Q ₅₈ is turned on, the transistor Q ₆₁ is turned on, the comparison result of the first comparator circuit (3) is Invalid. At the same time, the set / reset signal of the flip-flop circuit (4) becomes “H”,
The drive circuit (1U) (1V) (1W) operates. The transistor Q ₅₂ is turned on, the charge of the capacitor C starts to be discharged through the transistor Q _52. At the same time, transistor Q
₆₃ turns on, and the reference voltage V _T5 is a value V obtained by dividing the resistance R ₄ R ₅ R _6
T5ON (<V _T5OFF ). However, any one of the driving transistors Q ₁₅ Q ₂₅ Q ₃₅ turns on instantaneously, so that the driving transistor Q ₁₂ Q ₂₂ Q in the driving circuit (1U) (1V) (1W)
_Although the emitter potential of ₃₂ instantaneously drops to approximately the ground potential, its base potential cannot instantaneously drop due to its base-emitter parasitic capacitance, and its base-emitter potential difference is sufficient to turn on. . In other words, the flow the drive transistor _{Q 12 Q 15, Q 22 Q} 25, Q 32 Q is ₃₅ through current (large current) momentarily, the terminal voltage V _Rf of the detection resistor R _f are extremely large (> V _T1) . Therefore, the first comparator circuit (3) from the same comparison result under load for preventing the rotation of the motor (false signal) is obtained, since the comparison result becomes invalid by the transistor Q ₆₁ , First
The malfunction by the comparison circuit (3) is prevented. Then, at time t ₂ , the terminal voltage of the capacitor C
If V _C is equal to the reference voltage V _T5ON, the transistor Q ₅₈ is to turn off, the transistor Q ₆₁ is turned off, the first comparator circuit (3) in the comparison results is released disabled transistors Q ₅₉
Supplied to That is, the comparison result of the first comparator circuit (3) is to be invalid by the time t ₁ ~t ₂ determined by the hysteresis of the reference voltage V _T5. At the same time, the transistor Q ₆₃ is turned off, the reference voltage V _T5 is again resistor R ₄ value V _T5OFF obtained by dividing the R ₅ min. When the terminal voltage V _C of the capacitor C is finished it is discharged through the transistor Q _52, FIG. 1 circuit time t ₀
You will return to the previous state.

After that, when a load for preventing the rotation of the motor is applied again, the above operation is repeated.

As described above, when a load for preventing the rotation of the motor is applied, the drive transistors Q ₁₅ Q ₂₅ Q ₃₅ are turned off, that is, the drive circuits (1U) (1V) (1W) do not operate, and therefore, the power consumption is small. Becomes Further, when the driving transistor Q ₁₅ Q ₂₅ Q ₃₅ is through current turned on instantly flows, disabled for a time period determined by the hysteresis of the comparison result of the reference voltage V _T5 of the first comparator circuit (3), thus Therefore, malfunction due to the first comparison circuit (3) is prevented.

(G) Effects of the Invention According to the present invention, when a load for preventing rotation of the motor is applied, the drive transistor can be turned off to reduce power consumption, and further, the drive transistor is turned on and a through current flows. In such a case, there is obtained an advantage that the comparison signal of the first comparison circuit is invalidated and a malfunction by the comparison circuit can be prevented.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG.
3 is a circuit diagram showing a conventional circuit. (3)... First comparison circuit, (4)... Flip-flop circuit, (5)... Control circuit, (6).
(7) .... the second comparison circuit, (8) .... variable circuit, Q ₁₂ Q
₁₅ Q ₂₂ Q ₂₅ Q ₃₂ Q ₃₅ …… Drive transistor, Q ₁₆ Q ₂₆ Q ₃₆ …… Control transistor, R _f …… Detection resistor, C …… Capacitor.

Continuing from the front page (72) Inventor Juichi Juichi 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Masahiro Yasohara 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-4-46586 (JP, A)

Claims (1)

(57) [Claims] A detection resistor for detecting a drive current of a plurality of drive transistors provided for each drive coil for driving a motor; and a first reference signal for comparing a detection signal from the detection resistor with a first reference signal. And a control transistor that turns off the drive transistor based on a comparison signal of the first comparison circuit. A flip-flop circuit, and a comparison signal of the first comparison circuit A set circuit that sets the flip-flop circuit based on a control circuit that turns on and off the control transistor based on a set reset signal of the flip-flop circuit; and a capacitor based on a set reset signal of the flip-flop circuit. A charge / discharge circuit for charging / discharging a charge of the charge / discharge circuit; A comparison circuit that compares the first comparison circuit with the first comparison circuit based on the comparison signal of the second comparison circuit; and a comparison signal of the second comparison circuit. A reset circuit that resets the flip-flop circuit on the basis of: a variable circuit that changes the second reference signal to a first level or a second level based on a comparison signal of the second comparison circuit. When a load that hinders rotation of the motor is generated and the detection signal is larger than the first reference signal, the drive transistor is turned off using the comparison signal of the first comparison circuit. From this point, when the charge / discharge circuit charges the capacitor and the charge / discharge signal rises to the first level, invalidates the comparison signal of the first comparison circuit and turns on the drive transistor; From the point of time, when the charge / discharge circuit discharges the capacitor and the charge / discharge signal falls to the second level, the comparison signal of the first comparison circuit is invalidated, and the driving transistor Even when a through current flows from the power supply to the ground when the power supply is turned on, only during a period in which the charge / discharge current falls from the first level set by the variable circuit to the second level,
A motor drive circuit, wherein a malfunction of the first comparison circuit is prevented by invalidating a comparison signal of the first comparison circuit.