JPH01117680A - Dc motor driving circuit - Google Patents

Abstract

PURPOSE:To prevent hot water from directly outputting from a jar-pot by gradually raising the terminal voltage of a motor to a set value. CONSTITUTION:When a switch 2 is closed, a current is supplied to a heater 3 and a motor 40. A comparator 11 controls to so switch a transistor 5 that the terminal voltage of the motor 40 becomes a set value. Here, the set voltage is raised gradually to a set value from when the switch 2 is closed. Thus, since the rotating speed of the motor slowly rises, it can prevent hot water from directly outputting from a jar-pot.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a DC motor drive circuit built into equipment such as heaters and jar pots having high wattage resistance.

2. Description of the Related Art A conventional DC motor drive circuit includes a switch 170, a heater 120, and a rectifier stack 130, as shown in FIG.
A phase control circuit 160 consisting of an AC input terminal, a bidirectional thyristor 161, a bidirectional trigger diode 162, a resistor 163, a variable resistor 184, and a capacitor 166.
By connecting the series circuit with the AC power supply 110 and connecting the capacitor 140 and the motor 160 to the rectifier output terminal of the rectifier stack 130, the resistance value of the variable resistor 164 is changed, By changing the conduction angle of the bidirectional cyrisk, the effective value of the current flowing to the heater 120 is changed, and the capacitor 140 and the motor 16
When the applied voltage was set to 0 and the switch 170 was closed, the set voltage was applied to the motor 150.

Problems to be Solved by the Invention However, in such a conventional configuration, since the variable resistor 1θ4 only controls the conduction angle of the bidirectional thyristor 161, voltage fluctuations of the AC power supply 110 and heater 1
Variations in the resistance value of the variable resistor 164 and impedance of the motor 150 cause variations in the voltage applied to the motor 150, resulting in large variations in the rotational speed of the motor 150 with respect to the rotation angle of the variable resistor 164. Ta.

Moreover, as soon as the switch 170 is closed, the motor 15
Since the motor 160 rotates when a voltage is applied to the motor 160, if it is used to drive a hot water pump for a jar pot, a large amount of hot water will come out, which is dangerous, and therefore it cannot be used for such purposes. .

Note that if the capacitance of the capacitor 140 is increased, the voltage applied to the motor 150 will gradually increase;
Since the rotation of the motor 150 does not stop immediately when 0 is opened, it cannot be used.

An object of the present invention is to provide a DC motor drive circuit that solves these problems.

Means for Solving the Problems In order to solve the above problems, the DC motor drive circuit of the present invention divides the voltage of a voltage dividing circuit that divides the terminal voltage of the motor and the voltage of an integrating circuit that generates an integral waveform. It is equipped with a control circuit that bypasses the excess current due to full-wave rectification of the heater current using a power supply control element.

Operation According to the above configuration, since the terminal voltage of the motor is detected and the voltage applied to the motor is controlled, the set voltage can be accurately adjusted to the motor without being affected by variations in the voltage of the AC power supply or variations in resistance. can be applied to Furthermore, since the applied voltage rises slowly, the motor's rotational speed also rises slowly.As a result, when used to drive a hot water pump for a jar pot, hot water does not suddenly come out when the switch is pressed. It is extremely safe.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings. FIG. 1 shows a circuit diagram of a motor drive circuit according to an embodiment of the present invention, in which 1 is an AC power supply, 2 is a switch, 3 is a motor, 4 is a rectifier stack, and 5 is a transistor (corresponding to a current control element). ), 6 is a diode, 1o is a control circuit, a comparator 11°, transistors 12, 13 . capacitor 1
4. It is composed of resistors 15.16, 17.1B, and 19.20. Reference numeral 30 denotes a voltage dividing circuit, which is composed of resistors 31 and 33 and a variable resistor 32. 4o is the motor, 6
o is an integrating circuit, and a diode 61. Constant voltage diode 6
2. Capacitor 63.54, resistance 64.65, 66.6
7.

Next, the operation of the above circuit configuration will be explained. When the switch 2 is closed, a constant voltage is generated in the constant voltage diode 62, and the time constant (
1 second here), point a has the waveform shown in FIG. On the other hand, the heater current full-wave rectified by the heater 3° rectifier stack 4 passes through the diode e to the capacitor 16.
charge. Here, if the motor terminal voltage ratio divided by the variable resistor 32 is 1/n, then the voltage of the inverting input and the non-inverting input of the comparator 11 should be matched.
The terminal voltage of the motor is the voltage of the capacitor 53 (waveform at point a)
In the control circuit 1, the transistor 5 is turned on/off so that the value becomes n times as large as n times. Note that hysteresis is provided by resistors 15 and 20 so that the transistor 6 performs a switching operation.

In this case, the switching operation can be performed even if the resistor 15 is replaced with a capacitor. Also, variable resistor 3
n can be changed by changing the position of the intermediate terminal of 2,
Any voltage can be applied to the motor. Note that when the switch 2 is opened, the current supply from the AC power source 1 is cut off, so the terminal voltage of the motor 4o immediately disappears.

Effects of the Invention As described above, according to the present invention, the terminal voltage of the motor is detected and controlled so that the motor terminal voltage becomes the set voltage. is affected by variations in resistance values. Since there is a time period from when the switch is closed until the motor terminal voltage reaches the set voltage, for example, when applied to a motor for driving a jar pot pump, it is possible to accurately set the amount of hot water to be dispensed. Since the hot water starts to flow gradually, there is no splashing of the hot water and it is safe. Furthermore, when the switch is opened, the motor terminal voltage immediately disappears and the motor rotation stops, so the hot water does not stop flowing immediately.As a result, it is easy to use and practical. can.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a motor drive circuit showing an embodiment of the present invention, FIG. 2 is a waveform diagram of part a of the same motor drive circuit, and FIG. 3 is a circuit diagram of a conventional motor drive circuit. 1... AC power supply, 2... switch, 3...
... Heater, 4 ... Rectifier stack, 5 ... -
...Transistor, 6...Diode, 1o
...Control circuit, 3o...Voltage divider circuit, 4
o...Motor, 50...Integrator circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person
2 Figure 3L-1111 large nogθ

Claims (1)

[Claims] A series circuit of a switch, a heater, and an AC input terminal of a rectifier stack is connected to an AC power source, a current control element is connected to the rectifier output terminal of the rectifier stack, and a series circuit of a motor and a diode is connected to this current control element. Then, compare the voltage of the voltage dividing circuit that divides the terminal voltage of the motor with the voltage of the integrating circuit that generates the integral waveform, and if the voltage of the voltage dividing circuit is higher than the voltage of the integrating circuit, turn on the current control element, and if the voltage is lower. BaO
A DC motor drive circuit configured by connecting an FF control circuit to a control terminal of a current control element.