JPH02159970A - Power source for brushless blower motor - Google Patents

Abstract

PURPOSE:To protect a switching circuit from an overcurrent by installing a primary current detection resistor and a primary overcurrent reference voltage and primary current detector in a primary-side circuit and a secondary current detection resistor and a secondary overcurrent reference voltage and secondary current detector in a secondary-side circuit. CONSTITUTION:A primary current detection resistor 10 is installed in a primary- side circuit, change of the voltage of the primary current detection resistor 10 is detected by flow of an excess current in the primary side, said voltage is compared with primary overcurrent reference voltage, and output of the primary overcurrent detector 10 is fed back to a switching circuit 4 through a peak holding circuit 16 to control the output. A secondary current detection resistor 13 is installed in a secondary-side circuit, change of the voltage of the secondary current detection resistor 13 is detected by flow an overcurrent in the secondary side, said voltage is compared with secondary overcurrent reference voltage, and output of the secondary overcurrent detector 13 is fed back to the switching circuit 4 through the peak holding circuit 16 to control the output.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides an overcurrent detector for detecting and protecting overcurrent during driving of a brushless blower motor and instantaneous power failure of the input power supply. This relates to a power supply device for a brushless blower motor provided on the next side.

BACKGROUND OF THE INVENTION In recent years, power supply devices have become smaller and lighter due to high frequency switching due to advances in power device technology, and have come to be used for industrial and consumer purposes.

A conventional power supply device will be explained below.

FIG. 2 is a configuration diagram of a conventional power supply device, which is a non-insulated type power supply device. 1 and 1' are input terminals to which AC power is applied. 2 is a noise filter.

3 is a rectifying and smoothing circuit, and 4 is a switching circuit that chopper-controls the smoothed DC power supply. 5 is a transformer that supplies an output to the secondary side, and 6 is a secondary smoothing circuit. 7,7
' is an output terminal, 8 is an overvoltage detector, and 9 is an output reference voltage. 10 is a primary current detection resistor provided in the primary side circuit, and 13 is a secondary current detection resistor provided in the secondary side circuit. 11 is an overcurrent reference voltage, and 12 is an overcurrent detector.

Next, the operation will be explained.

An alternating current voltage is applied to the input terminal 1.1' and is supplied to the rectifying and smoothing circuit 3 via the noise filter 2. The rectified and smoothed DC voltage is supplied to the switching circuit 4, which switches the DC voltage at a constant frequency and applies a pulse voltage to the primary winding of the transformer 5. By smoothing the pulse voltage output from the secondary winding of the transformer with the secondary smoothing circuit 6, the voltage between the output terminals 7 and 7 is smoothed.
The DC output voltage is obtained at ′. In addition, as a control circuit, in the secondary side circuit, by comparing the output voltage of the secondary side with the output reference voltage 9, the output of the overvoltage detector 8 is fed back to the switching circuit 4, so that a constant voltage is applied to the secondary side. DC output power can be obtained. - The sum of voltages generated on the primary and secondary sides when current flows through the primary current detection resistor 10 and secondary current detection resistor 13 provided in the primary and secondary circuits, and the overcurrent reference voltage 11 The primary side circuit and the secondary side circuit can be protected from overcurrent by performing a comparison with the overcurrent detector 12 and feeding back the output of the overcurrent detector 12 to the switching circuit 4.

Problems to be Solved by the Invention In such a conventional configuration, when a brushless blower motor is connected and driven as a load on the secondary side, the overcurrent detector detects the sum of voltages caused by overcurrent on the negative side and the secondary side. Because it acts on the motor, the instantaneous response is poor, and the excessive current on the secondary side due to the starting current can damage the drive circuit of the brushless blower motor, and on the primary side, too much current due to a momentary power failure of the primary side input power can cause switching. Since there is a possibility of damaging the circuit, it is necessary to increase the withstand capability of the switching element, resulting in high cost and problems in terms of reliability.

The present invention solves these problems and provides a power supply for a brushless blower motor that can protect the switching circuit from secondary overcurrent protection when starting the brushless blower motor and from overcurrent during momentary power failure of the primary input power supply. The purpose is to provide equipment.

Means for Solving the Problems In order to achieve this object, the power supply device for a brushless blower motor of the present invention includes a primary current detection resistor in the primary side circuit, and detects the secondary current by causing an overcurrent to flow to the secondary side. Changes in the voltage of the resistor are detected and compared with the primary overcurrent reference voltage, and the output of the -order overcurrent detector is fed back to the switching circuit via the peak hold circuit to control the output.

Similarly, a secondary current detection resistor is provided in the secondary circuit,
When an overcurrent flows to the secondary side, a change in the voltage of the secondary current detection resistor is detected, and the output of the secondary overcurrent detector is controlled via a peak hold circuit by comparing it with the secondary overcurrent reference voltage. It has a configuration that allows feedback to the switching circuit to control the output.

With this configuration, an overcurrent on the primary side due to a momentary power failure of the input power supply can be detected by the primary overcurrent detector, and an overcurrent on the secondary side due to starting of the brushless blower motor can be detected by the secondary overcurrent detector. Here, since quick response is required for overcurrents on the negative side and secondary side, the peak value of at least one of the outputs of the negative overcurrent detector and the secondary overcurrent detector is held at the peak. By feeding back the output to the switching circuit, the output can be controlled with fast response.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a power supply for a brushless blower motor according to an embodiment of the present invention. Components that have the same configuration and operation as the conventional example shown in FIG. 2 are designated by the same numbers.

The configuration will be explained below.

In FIG. 1, 13 is a secondary current detector, 14 is a secondary overcurrent reference voltage, 15 is a secondary overcurrent detector, and 16 is a peak hold circuit.

- When a current flows through the primary current detection resistor 10 provided in the next-side circuit, a voltage change occurs in the -primary current detection resistor 10, and the primary overcurrent is detected by comparison with the primary overcurrent reference voltage 11. The output of the secondary side is controlled by feeding back the output of the converter 12' to the switching circuit 4 via the peak hold circuit 16. In addition, when a current flows through the secondary current detection resistor 13 provided in the secondary side circuit, a voltage change occurs in the secondary current detection resistor 13, and a voltage change occurs in the secondary current detection resistor 13 by comparison with the secondary overcurrent reference voltage 14. The output of the secondary current detector 15 is fed back to the switching circuit 4 via the peak hold circuit 16 to control the output on the secondary side.

Effects of the Invention As described above, according to the present invention, a primary current detection resistor, a primary overcurrent reference voltage, and a primary current detector are provided in the negative side circuit, and a secondary current detection resistor is provided in the secondary side circuit as well. By providing a current detection resistor, a secondary overcurrent reference voltage, and a secondary current detector, the brushless blower motor drive circuit is protected from overcurrent, and the switching circuit is protected from overcurrent caused by a momentary power failure of the input power supply on the next side. It can protect and increase reliability (
An improved power supply device for a brushless blower motor can be realized.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a brushless blower power supply device according to an embodiment of the present invention, and FIG. 2 is a configuration diagram of a conventional brushless blower power supply device. 1.1'... Input terminal, 2... Noise filter, 3... Rectifier and smoothing circuit, 4...
・Switching circuit, 5...Transformer, 6...
...Secondary smoothing circuit, 7゜7'...Output terminal, 8...Overvoltage detector, 9...Output reference voltage, 10...・-Next current detection resistor, 11'
...Primary overcurrent reference voltage, 12'...
Primary overcurrent detector, 13...Secondary current detection resistor, 14...Secondary overcurrent reference voltage, 15...
...Secondary overcurrent detector, 16...Peak hold circuit. Fig. 1 4-11 Sui, Notendero ■ 5-m-Transformer 6-112 request 5 bone recovery 8-11 pass 2 voltage East 纺上蓼 9- 嵯 conductive gourd ICL = - request Electric power supply temperature ℃ 491'--Friendly electrician reference voltage 12'--1 minute fLt boiling point 13--2; power resistor, 14--2 ；ni village? 5 糺鮮jun f 家种+s ---;d! hCurrent #, Bottle 6---Rake hold circuit diagram 2

Claims (1)

[Claims] a rectifying and smoothing circuit for rectifying and smoothing an AC power source; a switching circuit connected to the rectifying and smoothing circuit for switching the rectified and smoothed DC voltage at a constant frequency; and an output of the switching circuit being supplied to a primary winding. In a power supply circuit comprising a transformer and a secondary smoothing circuit for smoothing a secondary output supplied from a secondary winding of the transformer, primary overcurrent detection is performed by inputting a current from the rectifying and smoothing circuit. a secondary overcurrent detector into which the current from the secondary smoothing circuit is input; output sides of both the primary overcurrent detector and the secondary overcurrent detector are connected to a switching circuit; The output of at least one of the primary overcurrent detector or the secondary overcurrent detector limits the output of the switching circuit, and detects the DC output voltage on the secondary smoothing circuit side, and compares it with the output reference voltage. A power supply device for a brushless blower motor, comprising an overvoltage detector that controls an output of the switching circuit.