JPS647338Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a self-balancing device with protection against overscaling.

In automatic balancing devices, overscale protection means against excessive input and the like are required. FIG. 1 shows a circuit of an example of a main part of a known automatic balancing device having overscale protection means. In Figure 1, PB is a power booster that amplifies the deviation input;
BM is a servo motor, and a series resistor R is connected between PB and the drive coil of BM. MS is a micro switch connected across the resistor R. This switch is driven by the position of a pointer (not shown) that moves according to the rotation of the servo motor BM, and closes when the input signal is a normal value, shorting out the resistor R, and when over-range. When turned off, the resistor R is connected to the drive coil of the servo motor BM, limiting the rotational torque of the BM. This protects the servo motor BM, gears, etc. from excessive input.

Automatic balancing devices with such protection measures have been used in the past, but they have a limited lifespan because they use a mechanical switch called a micro switch MS.

(b) Since this method controls the motor torque by turning on and off the series resistor R, there are drawbacks such as the gain of the servo system changes and the dead zone becomes large when the micro switch MS is off. The present invention has been made to improve the above-mentioned drawbacks of the conventional example, and an embodiment of the present invention will be described in detail below with reference to FIG. 2.

In FIG. 2, IN is a terminal to which a deviation voltage ε between the input voltage and the feedback voltage described later is applied, and _U1 is a chopper amplifier composed of an amplifier _A1 , a switch SW, and a power supply OSC that drives this switch.
The deviation voltage applied from terminal IN is converted into an AC signal by this chopper amplifier. PB is a power booster consisting of a pair of transistors Q ₁ and Q ₂ ,
The output voltage of the chopper amplifier U ₁ is applied to this booster via a resistor R ₁ for power amplification.
BM is a servo motor, which is rotated in the direction in which the deviation input ε becomes zero by the output of the power booster PB applied to its drive coil. Note that this _U1 portion is not necessarily a chipper amplifier and may be a DC amplifier. FV is a feedback voltage generation circuit, which consists of a position detection slide resistor SR and variable resistors R ₂ and R ₃ connected in series to both ends of this resistor.
A reference voltage source V _R is connected to both ends of the series circuit. The connection point between the positive side of the reference voltage source V _R and the resistor R ₃ is connected to the circuit common. slide resistor
The slide S of the SR is driven by the rotation of the servo motor BM, and a voltage _E1 corresponding to the slide position is extracted from this slide.
The voltage E ₁ is used as a feedback voltage, and the difference between the voltage corresponding to E ₁ and the input voltage is applied to the terminal IN as a deviation signal ε.

U ₂ is an upper limit comparator consisting of amplifier A ₂ and resistors R ₄ and R ₅ , and the input terminal of amplifier A ₂ receives the voltage generated at the connection point between slide resistor SR and resistor R ₂ of the feedback voltage generating circuit FV. is applied through resistor R ₄ and the positive voltage supply +V is applied through resistor R ₅ . The voltage generated at the connection point of resistors R ₄ and R ₅ is
Assuming E ₃ , this voltage is 100
It is used as a set voltage corresponding to the cut-off point on the % side. _U3 is a lower limit ratio limiter consisting of amplifier _A3 and resistors _R6 and _R7 , and _the voltage generated at the connection point of slide resistor SR and resistor _R3 is connected to resistor _R6 at the (-) input terminal of amplifier A3. and a negative voltage source V- is applied through resistor _R7 . Resistors R ₆ and R ₇
Assuming that the voltage at the connection point is _E2 , this voltage is used as a set voltage corresponding to the break-off point on the 0% side of the slide resistor SR. Amplifier A ₂ (-)
Slide resistor at the input end and the (+) input end of _A3
Voltage E ₁ obtained depending on the position of slide S of SR
has been added. Comparators U ₂ and U ₃ compare the magnitudes of voltage E ₁ and set voltages E ₂ and E ₃ , and depending on the comparison result, comparators U ₂ and U ₃ produce the following outputs.

When E ₁ < E ₃ ...... Output of U ₂ + V Output of U ₃ - When E ₂ < E ₁ ...... Output of U ₂ - Output of U 3 + V _{E 3 <} E ₁ < E ₂ When... Output V of U ₂ - Output V of U ₃ OR is an OR circuit, with diodes D ₁ and D ₂ and resistor R ₈
and a voltage source V-. The diodes D ₁ and D ₂ have the same polarity, and one pole is connected to the comparator.
They are connected to the output terminals of amplifiers A ₂ and A ₃ constituting U ₂ and U _3, respectively, and the other poles are commonly connected to an output point P, which is connected to a voltage source V- through a resistor R ₈ .
It is connected to the. The potential at the output point P in this OR circuit becomes +V or V- according to the outputs of the comparators U ₂ and U ₃ as follows.

When one of the outputs of U ₂ and U ₃ is +V, the potential at point P is +V. When the outputs of U ₂ and U ₃ are both V-, the potential at point P is V-. LM is the transistor Q ₃ . ~Q ₅ is a voltage limiter consisting of Zener diodes Dz ₁ and Dz ₂ and diodes D ₃ and D ₄ . Output point P of the OR circuit OR
is connected to the base electrodes of transistors Q ₃ and Q ₅ through a resistor R ₉ , the collector of Q ₃ is connected to the base electrode of Q ₄ , and the voltage V is connected through a resistor R ₁₀ .
– is connected to. The collector electrode of the transistor Q ₄ is a Zener diode Dz ₁ and a diode D ₃
The collector electrode of the transistor Q ₅ is connected to the input terminal P ₁ of the power booster PB for power amplifying the output of the chip amplifier U ₁ through the series circuit of the Zener diode Dz ₂ and the diode D ₄ , respectively. has been done. The emitter electrodes of each transistor Q ₃ to _{Q 5} are connected to a common. In this voltage limiter LM, when the potential at the output point P of the OR circuit OR becomes +V, the transistors Q ₄ and Q ₅ turn on, and as a result, the voltage at the input terminal of the power booster PB increases to the level of the Zener diodes Dz ₁ and Dz ₂ . It is now clipped to the Zener voltage. Note that the diode D ₃ ,
_D4 is provided to block the base current of transistors _Q4 and _Q5 . The operation of the device of the present invention having such a configuration will be explained as follows.

The deviation input ε applied from the terminal IN is converted into an AC signal by the chip amplifier _U1 , and then the power is amplified by the power booster PB, and the power is amplified by the servo motor BM.
added to. The rotation of the servo motor BM is controlled by a position detection slide resistor so that the deviation input ε becomes zero.
Move slide S of SR. The voltage E ₁ taken out from the slide S is applied to upper and lower limit comparators U ₂ and U ₃ and compared with upper and lower limit set voltages E ₃ and E ₂ , respectively. When E ₁ is within the range of E ₂ and E ₃ ,
The output voltages of the upper and lower limit comparators U ₂ and U ₃ are V- as described above, and the potential of the output point P of the OR circuit OR is V-. As a result, transistors Q ₄ and Q ₅ of the voltage limiter LM are turned off and this LM circuit does not operate, and as a result, the servo system operates normally. Next, for some reason, the deviation input ε exceeds the measurable range of 0 to 100% and becomes overscaled, and the relationship between the voltage E ₁ obtained by the position detection slide S and the upper limit setting voltage E ₃ changes. When E ₁ < E ₃ , the output of comparator U ₂ is +V as mentioned above.
becomes. Also, the relationship between E ₁ and lower limit setting voltage E ₂ is E ₂
When <E ₁ , the output of comparator U ₃ becomes +V as well. As a result, in either of the above two states, the potential at the output point P of the OR circuit OR becomes +V, and the transistors _Q4 and _Q5 of the voltage limiter LM are turned on. If Q ₄ and Q ₅ are turned on and the voltage applied to the power booster PB is higher than the Zener voltage of the Zener diodes Dz ₁ and Dz ₂ , Dz ₁ ,
Dz ₂ are each turned on. As a result, the voltage at the input terminal _P1 of the power booster PB is clipped to the Zener voltage of the Zener diodes _Dz1 and _Dz2 .
As a result, the rotational torque of the servo motor BM is suppressed to a low constant value, thereby preventing burnout of the BM or wear of gears, pulleys, etc.

In addition, in the device of the present invention, if the input value is within the measurable range, even if the potential at the output point P of the OR circuit OR becomes (+), the chip amplifier
If the output of U ₁ is smaller than the Zener voltage of the Zener diodes Dz ₁ and Dz ₂ , Dz ₁ and Dz ₂ remain in the off state, so the operation is similar to the case without the voltage limiter LM. In other words, there is a characteristic that the dead zone does not increase.

As described above, the present invention uses a Zener diode to clip the voltage at the input terminal of the power booster, so it can be expected to have high reliability over a long period of time compared to conventional protection methods using mechanical switches. Further, it is possible to obtain an automatic balancing device equipped with an overscale protection means, which has the characteristics that the gain of the servo system remains unchanged in the range of the limit voltage with input values that can be balanced, and the dead zone does not become small.

[Brief explanation of drawings]

FIG. 1 is a connection diagram of the main parts of a conventional device, and FIG. 2 is an electrical connection diagram showing an embodiment of the device of the present invention. PB...Power booster, BM...Servo motor, SV...Feedback voltage generation circuit, S...Position detection slide, _U2 , _U3 ...Comparator, OR...OR circuit, LM...Voltage limiter, Dz ₁ , Dz ₂ ... Zener diode.

Claims (1)

[Scope of utility model registration request] The deviation voltage between the input signal and the feedback voltage obtained according to the slide position of the position detection slide is applied to the servo motor via a power booster, and the voltage obtained from the position detection slide corresponds to the upper and lower limit values set in advance. An upper limit comparator and a lower limit comparator that compare the set voltage with the set voltage, an OR circuit connected to the output terminals of the upper limit comparator and the lower limit comparator, and their conduction is controlled by the potential at the output point of this OR circuit. An automatic balancing device comprising a voltage limiter consisting of a transistor and a Zener diode connected between the transistor and the input end of the power booster for clipping the voltage applied to the power booster in the event of overscaling.