JP2508845Y2 - DC motor deceleration braking device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a deceleration braking device for a DC motor whose rotation speed is controlled by varying a power supply voltage.

<Prior Art> Conventionally, for example, a gas water heater is provided with a blower for feeding air, and when controlling the hot water temperature, the air amount according to the gas discharge amount, the rotation speed of the DC motor of the blower, and the power supply voltage are varied. It was obtained by controlling the air flow rate by controlling the. Therefore, when the discharge amount of gas is reduced, the DC motor must be rapidly decelerated accordingly, and the gas / air mixture ratio cannot be maintained optimally, resulting in abnormal combustion. In order to prevent this, when the power supply voltage is lowered, deceleration braking is applied to the DC motor.

Fig. 4 shows this as an example.
Is a direct-current drive power supply, which is inserted between a variable direct-current power supply circuit VD ₁ in which the output voltage is variable and is sent in one direction in response to a speed command from a rotation speed setting device (not shown), and between the output end and the circuit ground. An output capacitor C ₁₁ is provided, and the terminal voltage of the capacitor C ₁₁ is supplied to the DC motor 11 via the braking circuit 13 as a power supply voltage. In the braking circuit 13, a diode D ₁₁ is inserted in the forward direction between the output end of the capacitor C _{11 and} the input end of the DC motor 11, and the PNP transistor Q _{11 is connected} between the cathode of the diode D ₁₁ and the circuit ground. Emitter-collector and braking resistor R ₁₂
Was inserted in series, the base of the transistor Q _11, as well as connected to the anode of the diode D _11, and the circuit through the resistor R ₁₁ ground, when the power supply voltage is lowered, turned off the diode D _11, the transistor Q ₁₁ by applying a base current to turn on the transistor Q _11, the DC motor 11 by supplying a current to reverse torque is generated to decelerate the brake applied through a braking resistor R _12, so as to decelerate the DC motor 11 There is.

<Problems to be Solved by the Invention> However, in the configuration as described above, the base current of the transistor Q ₁₁ changes depending on the terminal voltage of the motor 11 and the resistance R ₁₁ , so that the transistor Since there is variation in the operation of the device and it operates in the unsaturated region, loss occurs, a transistor with a large safe operating area (ASO) is required, and an expensive element must be used. , Diode D ₁₁ is DC drive power supply 12
Since it is inserted in series between the output end of the motor and the input end of the motor 11, a loss due to its forward voltage is generated.For example, this loss is 20W for the motor 11, DC20V for the power supply voltage, and 1 for the current.
If the forward voltage of A and the diode D ₁₁ is set to 1 V, it becomes 1 W, which causes a loss of 5%, which cannot be ignored, and there is a problem that the motor efficiency is reduced. Further, since the resistor R _{11 is} also connected in series to the output end of the DC drive power source 12, current always flows to cause a loss, and the resistor R ₁₁ has a large resistance value in order to reduce the loss. Then, when the power supply voltage is lowered,
The discharge time constant of the capacitor C ₁₁ becomes large and the transistor Q
_The time it takes to switch from ₁₁ off to on increases,
The timing of applying deceleration braking to is delayed. This means that it takes longer to reach the set deceleration speed, and the motor 11 cannot be decelerated quickly. Conversely, if the value of the resistor R ₁₁ is set small, the followability to the drop in the power supply voltage is Although it is improved, there is a problem that the current that constantly flows becomes large and the loss further increases.

An object of the present invention is to solve the above-mentioned problems, reduce the loss in a steady state and improve the motor efficiency, and at the time of decelerating the motor, decelerate and brake which stably and quickly follows the drop in the power supply voltage. Is to provide something that can be added.

<Means for Solving the Problems> To achieve the above object, the present invention compares the output obtained by differentiating the voltage change of the DC drive power supply supplied to the DC motor with a preset reference voltage connected to the constant voltage power supply. A braking signal circuit for sending a braking signal and a braking circuit in which a braking resistor and a transistor are inserted in series between terminals of a DC motor are provided, and the transistor is turned on by the braking signal to turn on the DC signal. This is configured to apply deceleration braking to the motor.

<Operation> With the above configuration, when the power supply voltage is lowered, the output obtained by differentiating the voltage change is detected by comparison with the reference voltage, and a braking signal is sent to turn on the transistor to apply deceleration braking to the DC motor. At this time, since the transistor stably supplies the base current with the constant voltage power source, the DC motor is stably and quickly decelerated to the deceleration set rotation speed.

<Embodiment> An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In FIG. 1, reference numeral 1 is a DC motor such as a brushless motor or a commutator motor (hereinafter simply referred to as a motor),
Reference numeral 2 is a DC drive power source for supplying a DC power source to the motor 1. This is a variable direct-current power supply circuit VD ₁ in which the output voltage is varied (for example, 0 to 40 V) according to a command from a rotation speed setting device (for example, 0 to 40 V) and is sent out in only one direction, and between this output end and the circuit ground. , inserted output capacitor C ₁ Tokyo, the motor 1 between the output terminal and circuit ground the capacitor C ₁
Connect the is adapted to apply to the motor 1 the terminal voltage of the capacitor C ₁ as a power supply voltage. Reference numeral 3 denotes a braking signal circuit that detects a decrease in the power supply voltage in order to reduce the rotation speed of the motor 1 and outputs a braking signal. This is to insert a capacitor C ₂ and a first resistor R ₁ in series between the output end of the DC drive power source 2 and the circuit ground, and output the connection point (point a) of this capacitor C ₂ and resistor R _1. As an end, a differentiating circuit 3a adapted to send out an output voltage Vd which is obtained by differentiating the change in the input voltage, and an inverting input terminal of a comparator COM composed of an operational amplifier of a single power source are connected to the output terminal of this, and a resistor R Connected to the constant voltage power supply V _C via ₂ and the third and fourth resistors R ₃ , R inserted in series between the constant voltage power supply V _C and the circuit ground at the non-inverting input terminal of the comparator COM. _And a comparator circuit 3b in which the reference voltage Vref preset by the resistors R ₃ and R ₄ is input by connecting the connection point of ₄ and the output terminal of the comparator COM to the comparator COM. When the inputs Vd and Vref have a relationship of Vd <Vref, the "H" level output signal is sent as a braking signal. There. The resistors R ₁ , R ₂ , R ₃ , and R ₄ are of high resistance, and the resistors R ₁ and R ₂ and the resistors R ₃ and
The voltage division ratio for dividing the constant voltage power supply Vc by R ₄ is (R ₁ /
(R ₁ + R ₂ ))> (R ₄ / (R ₃ + R ₄ )). Further, the reference voltage Vref is set to a value at which the comparator COM does not operate to output a braking signal due to the ripple of the voltage of the DC drive power source 2 so that the drop in the power source voltage during deceleration can be accurately compared and detected. Has become. Reference numeral 4 is a braking circuit adapted to apply electric braking to the motor 1 by the braking signal of the braking signal circuit 3. This is because a braking resistor R ₆ and a collector-emitter of a grounded emitter transistor Q ₁ are inserted in series between the input end of the motor 1 and the circuit ground, and a base resistor R ₅ is added to the base of the transistor Q _1.
The output terminal of the braking signal circuit 3 is connected via the above, and when the power supply voltage is lowered, the transistor Q ₁ is turned on by the braking signal and the motor 1 is decelerated by electric braking. Reference numeral 5 is a control power supply circuit configured to output the constant voltage power supply Vc to the braking signal circuit 3.

Next, the operation will be described. When a power switch (not shown) is turned on, a constant voltage power supply Vc is supplied from the control power supply circuit 5 to the braking signal circuit 3, and the constant voltage power supply Vc is connected to the resistor R ₁
The voltage Vd (= Vc × R ₁ / (R ₁ + R ₂ )) divided by R ₂ and R ₂ is output to the inverting input terminal of the comparator COM of the comparison circuit 3b, and at the non-inverting input terminal, The reference voltage Vref (= Vc × R ₄ / (R ₃ + R ₄ ) preset by the resistors R ₃ and R ₄ is output. The output signal of the comparator COM that receives both of these outputs Vd and Vref is Since both inputs Vd and Vref are in the relationship of Vd> Vref, they are at “L” level and no braking signal is output.
Transistor Q ₁ is held in the off state.

On the other hand, in the DC drive power supply 2, when a speed command for the rotation speed S ₁ is sent from a rotation speed setting device (not shown), the variable DC power supply circuit VD _{1 that} receives the speed command outputs the output voltage Vs corresponding to the rotation speed S _{1. 1} is output to the motor 1 as a power supply voltage from the output end via the capacitor C ₁ , the motor 1 is started and accelerated, and the rotation speed thereof reaches S ₁ to become the steady rotation.

At this time, the capacitor C ₂ of the differentiating circuit 3a is connected to the output voltage Vs
Is charged by _1, the voltage Vd at the output end of the fine fraction circuits 3a (a point) is once increased to a value corresponding to Vs _1, the voltage to which dividing the constant voltage source Vc by the resistors R ₁ and R ₂ Hold down. Therefore, both inputs Vd and Vref of the comparator COM maintain the relationship of Vd> Vref, and the braking signal is not output.

Next, a case where the motor 1 is decelerated will be described. When the speed command for the rotation speed S ₂ is output from the rotation speed setting device (not shown) at the time t _{1 in} FIG. ₂ to decelerate to the rotation speed S ₂ from the above steady rotation (rotation speed S _{1 in} this example). , The variable DC power supply circuit VD ₁ of the DC drive power supply 2 which receives this lowers to the voltage Vs ₂ corresponding to the rotation speed S ₂ and tries to supply to the capacitor C ₁ , but at this time, the terminal voltage of the capacitor C ₁ Since it is higher (Vs ₂ <Vs ₁ ), the power supply of the variable DC power supply circuit VD ₁ is stopped, and therefore the capacitor C ₁ is
The electric charge is instantly discharged along the route of C ₁ → 1 → circuit ground → C ₁ , and the terminal voltage of the capacitor C ₁ and the motor 1 is generated in the resistance of the winding of the motor 1 by the current flowing during the steady rotation. The amount of voltage drop has decreased (t _{1 in} Fig. 2 (a)).
Time point), and becomes equal to the induced voltage of the motor 1 during steady rotation.

On the other hand, the capacitor C ₂ of the differentiating circuit 3a also changes its charge by C ₂ →
1 → Circuit ground → R ₁ → C ₂ path and C ₂ → 1 → Circuit ground → 5 →
The voltage Vd at the output end (point a) of the differentiating circuit 3a is discharged with a path of R ₂ → C ₂ and has a waveform that is rapidly attenuated by this discharge current, and the voltage Vd falls and the inverting input terminal of the comparator COM. Will be output to (Fig. 2 (C)). Therefore, the above output voltage
Vd has a relationship between the reference voltage Vref and Vd <Vref at the time t 2 in FIG. ₂ , and the output signal of the comparator COM is inverted from “L” to “H” level (FIG. 2 (d)). That is, the braking signal circuit 3 outputs a braking signal. Transistor Q _{1, which} receives this through the base resistor R ₅ to the base, turns on and closes the terminals of motor 1, and motor 1 is connected to braking resistor R ₆ by the terminal voltage.
A reverse torque-generating current flows through the motor 1 to act as a generator, and dynamic braking is applied. The kinetic energy of the motor 1 is converted into thermal energy by the braking resistor R ₆ and consumed to decelerate the motor 1. The speed is quickly reduced to the set rotation speed (S ₁ → S _{2 in} this example) (Fig. 2 (b)).

The output voltage Vd of the differentiating circuit 3a is
As the discharge of C ₂ progresses, it further decreases, and as the discharge current decreases, it starts to rise, becomes larger than the reference voltage Vref (Vd> Vref) at time t _{3 in} FIG. 2, and the output signal of the comparator COM becomes “L”. "Invert to the level, that is, stop the output of the braking signal,
The transistor Q ₁ is turned off to stop the dynamic braking, and the rotation speed of the motor 1 also shifts to the steady rotation of S _{2 with} a slight delay from the time t ₃ (Figs. 2 (c) and 2 (d)). (B)). Next, the output voltage Vd rises to a value (= Vc × R ₁ / (R ₁ + R ₂ )) obtained by dividing the constant voltage power supply Vc by resistors R ₁ and R ₂ and is held stable (Fig. 2). (C)).

On the other hand, the terminal voltage of the capacitor C ₁ also drops due to the discharge to the braking circuit 4, and becomes a voltage Vs ₂ corresponding to the rotational speed (S ₂ ) set to be decelerated at the time point t _{3 in} FIG. 2 (see FIG. 2 ( I)).

As described above, when the power supply voltage is reduced to decelerate the motor 1, the voltage decrease, that is, the voltage change is differentiated and detected by comparison with the reference voltage. However, the braking signal can be output accurately and stably. Moreover, since the reference voltage is set to a value that prevents malfunction due to the ripple of the power supply voltage, comparison detection can be performed without causing malfunction. Further, since the braking signal is sent from the constant voltage power source, the base current of the transistor of the braking circuit can be stabilized and on / off controlled regardless of the change in the power source voltage of the motor 1.

By the way, it was confirmed that the deceleration time to reach the rotation speed (eg S ₁ → S ₂ ) during deceleration could be shortened to 1/10 by the configuration shown in FIG. 4 and FIG. ing.

FIG. 3 shows another embodiment, in which the braking signal circuit 6
1 is the same as that of FIG. 1 except that the same members are designated by the same reference numerals and different points from the braking signal circuit of FIG. 1 will be described.
The constant voltage diode ZD ₁ is inserted between the output end of the capacitor and the capacitor C ₂ of the differentiation circuit 3a with the cathode connected to the capacitor C ₂ side, and the comparison circuit 6b outputs the output of the differentiation circuit 3a to which the resistor R ₂ is connected. Insert capacitor C ₃ between the end (point a) and circuit ground,
When the amount of decrease in the power supply voltage (that is, the amount of decrease in rotation speed) exceeds the Zener voltage of the constant voltage diode ZD ₁ Differentiation circuit 3a
When the output voltage Vd is sent from the output terminal of the comparator and the relationship of the reference voltage Vref and Vd <Vref is satisfied, the output signal of the comparator COM is inverted to "H" level and the braking signal is sent. Then, as the discharge of the capacitor C ₂ progresses, the output voltage
Vd drops further than the reference voltage Vref, and when the output voltage Vd rises as the discharge current decreases, the output voltage Vd rises gradually due to the charging time constant of the capacitor C ₃ , and the relationship of Vd> Vref Until it becomes ((Fig. ₂ t ₂ ~
(time width of t ₃ ) is lengthened (that is, braking time is lengthened)
It has become.

According to this embodiment, since the output time of the braking signal can be lengthened, even when the inertial force of the rotation of the motor 1 and the load of the motor 1 is large, deceleration braking is added,
Deceleration It is possible to quickly reach the set rotation speed. Moreover, it is possible to prevent so-called excessive deceleration braking that occurs when the reduction range of the rotation speed is small, and reduce the loss.If the reduction range of the rotation speed is always large, the constant voltage diode ZD ₁ may be omitted. it can.

Although the comparator COM has been described as having a single power source in the above embodiments, it may be of a dual power source, and the present invention is not limited to the above embodiments, and various modifications are possible without departing from the scope of the invention. Of course, it can be modified.

<Advantages of the Invention> According to the present invention, the braking signal circuit and the braking circuit can be formed without interposing a loss-generating element in the power supply path of the DC motor, so that the power loss can be reduced. it can. Moreover, when the power supply voltage drops, the braking signal circuit quickly outputs the braking signal to turn on the braking circuit to apply deceleration braking to the DC motor, so that it is possible to enhance the followability to the decrease in the power supply voltage. . Further, the braking signal circuit is configured to compare and detect the output obtained by differentiating the voltage change amount and the reference voltage and send out the braking signal. Therefore, even if the deceleration is performed at any rotation speed, the time change amount of the voltage does not change. If they are the same, the braking signal can be sent at the same detection time.

This has a great effect that it can be applied to a device such as a gas water heater, which must optimally and rapidly variably control and maintain the mixing ratio of gas and air according to the discharge amount of gas. Have. A braking signal is sent to the base of the transistor that turns on / off the braking circuit from a braking signal circuit that operates by being connected to a constant-voltage power supply, so that the base current can flow stably and the on / off operation is saturated. Since it can be performed in a region, can be applied to a device having a small safe operation region, and can be configured with a highly versatile element, it can be inexpensive. Further, since the braking signal circuit can be configured only by a member that causes a minute power loss due to the constant voltage power source in the steady state, the loss can be reduced and the motor efficiency can be further improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a time chart diagram explaining the operation of FIG. 1, FIG. 3 is a block diagram showing another embodiment of the present invention, and FIG. It is a block diagram which shows a prior art example. 1, 11; DC motor, 2, 12; drive power circuit, 3, 6; braking signal circuit, 4, 13; braking circuit, 5; control power circuit, 3a; differentiating circuit, 3
b, 6b; comparison circuit,

Claims (1)

(57) [Scope of utility model registration request] 1. A direct-current motor connected to a direct-current drive power source, the rotation speed of which is controlled by varying the power-source voltage, and a braking resistor and a collector / emitter of a transistor connected in series between terminals of the motor. A circuit and the above DC drive power source, a capacitor and a first resistor are connected in series, and a differential circuit for differentiating and outputting a change in the power source voltage from the connection point of the capacitor and the first resistor; The output terminal of the differentiating circuit is connected to the inverting input terminal of the comparator composed of an operational amplifier, and is also connected to the constant voltage power supply via the second resistor, and the non-inverting input terminal of the comparator is connected to the constant voltage power supply. The connection point of the third and fourth resistors inserted in series between the circuit grounds is connected to connect the output of the differentiating circuit and the reference voltage output from the connection point of the third and fourth resistors. In comparison, the output of the differentiation circuit is the reference voltage. When more drops, brake signal deceleration braking device of a DC motor comprising; and a brake signal circuit comprising a comparator circuit which is adapted to deliver to the base of the transistor.