KR900005496Y1 - Limiting circuit for initial surge current - Google Patents

Abstract

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Description

Initial Inrush Current Limiting Circuit of Heating Equipment

1 is an embodiment circuit diagram of the present invention.

2 is a voltage waveform diagram of each point of FIG.

(A) is a conventional circuit diagram, (b) is a PTC characteristic diagram, (c) is a current characteristic diagram of (a).

* Explanation of symbols for main parts of the drawings

1: driving unit 2: rectifying unit

3: smoothing part 4: comparing part

5: discharge unit TS: thyristor

R ₁ , -R ₁₁ : Resistance ZD: Zener Diode

CP: Comparator HT: Heater

TH: Thermostat C ₁ -C ₃ : Condenser

D ₁ , D ₂ : Diode Q ₁ : Transistor

The present invention relates to an initial inrush current limiting circuit by limiting an initial inrush current, which is a characteristic of a PTC element, in a heating apparatus using a PTC (Positive Temperature Characteristic) element.

In the conventional heating apparatus using the PTC element, the PTC heater HT is directly connected to the power supply in parallel with the fan motor M as shown in FIG. 3 (a). temperature range, such as degree _{(b) (T a -T b} ) the resistance value is reduced, but the initial several seconds as in the above temperature in degrees third being has a characteristic that the resistance value is increased (c) is a stabilized current (i _n) When a large inrush current of several times flows, and the temperature of the PTC heater (HT) rises and the resistance increases, the resistance value of the heat loss caused by the wind of the fan morty (M) and the heat generation amount of the PTC heater (HT) is the same ( In R ₀ ), the current flowing through the PTC heater HT is kept constant at a stable oscillation i _n . However, as the initial inrush current reaches several seconds and the maximum inrush current (i _m ) is about 15-30A depending on the power supply voltage, there is a possibility that the peripheral electronic device malfunctions due to the instability of the power supply. There was a problem that the safety of the power line can not be guaranteed.

The present invention is to solve such a problem, and when the start of the heating device using the PTC element pulsed AC voltage applied to the PTC heater, when the temperature of the PTC heater reaches a certain temperature is normal As designed to apply power, the following describes the configuration and operation of the present invention in detail.

The AC power source AC is applied to both ends of the drive unit 1 for driving the fan motor M and the PHT heater HT, respectively, and is applied to the rectifying unit 2, and the output of the rectifying unit 2 is smoothed. (3) is applied to the smoothing and at the same time as the power supply of the comparator 4, the output of the comparator 4 is applied to the discharge part 5, while being configured to be applied to one side input of the driver 1 do.

In the above configuration, the comparator 4 divides the output voltage of the rectifier 2 into resistors R ₉ (R ₁₀ ) and is applied to the inverting input terminal (−) of the comparator CP, while the resistor R ₈ is applied. And connected to the non-inverting input terminal (+) of the comparator (CP) through the charging circuit of the capacitor (C ₂ ), the discharge unit 5 is the output of the comparator (4) reverse current prevention diode (D ₂ ) Is applied to the base of the transistor Q ₁ through the charging circuit of the resistor R ₅ and the capacitor C ₁ and the bias resistor R ₆ (R ₇ ), and the comparator CP in the comparator 4. The non-inverting input terminal (+) voltage of is connected to the collector of the transistor Q ₁ through the resistor (R ₁₁ ), the drive unit 1 is the output of the comparator (4) is a resistor (R ₃ ) (R ₄ ) is applied to the gate terminal (G) of the thyristor (TS), the AC power source (AC) is the connection of the contact (a) (b) is converted according to the resistance (R ₁ ), thyristor (TS) and temperature Connected to PTC Heater (HT) through Thermostat (TH) do.

In the present invention configured as described above, when the AC power source AC is input and applied to the rectifying unit 2, it is half-wave rectified by the diode D ₁ and the voltage is lowered to the resistor R ₂ to be applied to the smoothing unit 3. In the smoothing section 3, the output of the rectifying section 2 is smoothed by the capacitor C ₃ , stabilized by the zener diode ZD, and supplied to the DC power supply of the comparator 4. The reference DC voltage applied to the comparator 4 and divided by the resistors R ₉ and R ₁₀ is applied to the inverting input terminal (-) of the comparator CP, and the ratio of the comparator CP is applied. The comparison voltage charged to the capacitor through the resistor R ₈ is applied to the inverting input terminal (+).

Initially, the reference voltage applied to the inverting input terminal (-) is higher than the comparison voltage applied to the non-inverting input terminal (+), so that the output of the comparator CP is outputted with a 'low' level, and this 'low' level signal Is applied to the discharge unit 5 and the drive unit 1, the transistor Q ₁ in the discharge unit 5 is 'off' so that the discharge unit 5 does not operate and the thyristor TS is also applied to the drive unit 1. It is 'off' so that the AC power source AC is not supplied to the PTC heater HT. Thereafter, as shown in FIG. _2A , a voltage is charged to the capacitor C ₂ through the resistor R ₈ , and the comparison voltage applied to the non-inverting input terminal (+) of the comparator CP is the inverting input terminal (−). When the output voltage of the comparator CP becomes 'high' level when it is higher than the reference voltage V _n applied to the voltage, and is applied to the discharge part 5, the 'high' level signal is reversed as shown in (b) of FIG. The capacitor C ₂ is charged through the current blocking diode D ₂ and the resistor R ₅ , while the gate terminal G of the thyristor TS is connected via the resistor R ₃ and R _{4 in the} driving unit 1. ) And the thyristor TS is conducted so that the AC power source AC is connected through the contacts a of the resistor R ₁ , the thyristor TS, and the thermostat TH as shown in FIG. It is applied to PTC heater HT and this PTC heater HT is heated.

On the other hand, the capacitor in the discharge part 5, the capacitor (C ₁₎ reaches a voltage that may conduct the transistor (Q _1), the voltage to be charged is a transistor (Q ₁₎ conducting the comparison unit (4) to within the (C ₂ ) Is discharged through the resistor (R ₁₁ ) and the transistor (Q ₁ ) in the discharge section 5, the comparison voltage of the non-inverting input terminal (+) of the comparator (CP) of the power generation input terminal (-) Lower than the reference voltage (V _n ), the output of this comparator (CP) is converted back to the 'low' level. Accordingly, the voltage charged in the capacitor C ₁ in the discharge part 5 is also discharged through the resistor R ₆ , so that the transistor Q ₁ is 'off', and the thyristor TS in the driving part 1 is also 'off'. AC power AC applied to the PTC heater HT is cut off, and the DC voltage output from the rectifier ₂ is charged to the capacitor C ₂ through the resistor R _{6 in the} comparator 4. The above operation is repeated.

Therefore, at initial startup of the PTC heater HT, an AC power supply voltage is applied to the PTC heater HT in the form of a pulse as shown in FIG. 2C, and the temperature of the PTC heater HT is raised to a constant level. When the temperature is reached, the thermostat TH in the driving unit 1 operates to switch from the contact point a to the contact point b so that a normal AC voltage is applied to the PTC heater HT.

As described above, the present invention is a heating apparatus using a PitiC heater, restricts the initial inrush current flowing to the PitiC heater by controlling the AC voltage and current applied to the PitiC heater during initial startup, and the PitiC heater is a constant temperature When the temperature rises above, the thermostat operates and normal AC power is applied to the PTC heater to prevent malfunction of surrounding electronic devices and to improve safety to prevent fire on the power line. It is a useful design with advantages.

Claims (4)

The rectifier 2 rectifies AC power, the smoothing part 3 for smoothing and stabilizing the output of the rectifying part 2, and the driving voltage is supplied from the smoothing part 3, and the reference voltage and charge arbitrarily set. In the output state of the comparator 4 which compares the comparison voltage by a circuit, the discharge part 5 which discharges the comparative voltage of the comparator 4 by the output of this comparator 4, and the comparator 4 Accordingly, the initial inrush current of the heating apparatus is characterized by comprising a drive unit 1 for interrupting an AC voltage applied to the PTC heater HT and applying a normal AC power when the PTC heater HT rises above a predetermined temperature. Limiting circuit. The comparator 4 according to claim 1, wherein the output voltage of the rectifier 2 is divided by the resistors R ₉ and R ₁₀ and applied to the inverting input terminal (-) of the comparator CP. A voltage charged to the capacitor C ₂ through the resistor R ₈ is applied to the non-inverting input terminal (+) of the power supply), and the output of the comparator CP is connected to one side of the discharge part 5 and the driving part 1. Initial inrush current limiting circuit of the heating mechanism, characterized in that configured to be applied to each input. The discharge part ₅ is charged with the output of the comparator part 4 to the capacitor C ₁ through the reverse current prevention diode D ₂ and the resistor R ₅ , and this charging voltage is biased. Through the resistors R ₆ and R ₇ the collector is applied via the resistor R ₁₁ to the base of the transistor Q ₁ connected to the non-inverting input terminal (+) of the comparator CP in the comparator 4. Initial inrush current limiting circuit of the heating apparatus, characterized in that the configuration. The driving unit 1 according to claim 1, wherein the output of the comparator ₄ is applied to the gate terminal G of the thyristor TS through the resistors R ₃ and R ₄ , and the AC power source AC is applied. Heating is characterized in that configured to be applied to the PTC heater (HT) through the smostat (TH) that the connection of the contact (a) (b) is converted according to the resistance (R ₁ ), thyristor (TS) and temperature Initial inrush current limiting circuit of the instrument.