JPH05304796A - Chopper device - Google Patents

Abstract

PURPOSE:To reduce fluctuation of output voltage even if an input voltage fluctuates in a chopper device which turns on or off the switching element which is placed between a DC power supply and a load for adjusting the output voltage. CONSTITUTION:The title device is provided with a voltage control means 16 which controls the on/off duty ratio of switching elements 4 and 5 corresponding to the deviation between a voltage reference Vr and an output voltage Vc and at the same time a compensation means 22 which performs control so that the duty ratio is inversely proportional to input voltages Vi of the switching elements 4 and 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chopper device for adjusting the output voltage by controlling the energizing time of a switch element according to the deviation between a voltage reference and the output voltage.

[0002]

Chopper devices are widely used in devices for controlling DC voltage. In addition, it is often used in combination with an uninterruptible power supply or an inverter device for motor drive. As an example, FIG. 2 shows the configuration of a step-down chopper and its control circuit.

In FIG. 2, 1 is an AC voltage source, 2 is a rectifier, 3 is an input capacitor, 4 and 5 are chopper elements in which diodes are connected in antiparallel, 6 is a DC reactor, 7 is an output capacitor, 8 Is a load input contactor or switch, 9 is a load motor, 10 is a deceleration switch, 11 is a deceleration resistance, and 12 is a diode.

[0004] 13 voltage detector insulated for detecting the chopper output voltage V _c, 14 a voltage reference setter for setting a voltage reference V _r, 16 is the voltage reference V _r and the output voltage V _c
A voltage control amplifier for generating a chopper control signal E _c according to the voltage deviation of the pulse generator 17, a pulse generator 17 for generating ON / OFF pulses of the chopper elements 4 and 5 according to the chopper control signal E _c , and 18 is the above-mentioned ON Amplifies the / OFF pulse,
It is a pulse amplifier which is given to the chopper elements 4 and 5.

Further, 19 is an insulated voltage detector for detecting the chopper input voltage V _i , 20 is a hysteresis comparator for deciding ON / OFF of the deceleration switch according to the detected value of the chopper input voltage, and 21 is a comparator. It is a power amplifier that amplifies 20 signals and gives them to the deceleration switch.

In the above structure, the voltage control in the normal power running operation is performed by turning on / off the chopper element 4, and the voltage control in the regenerative operation during deceleration is performed by turning on / off the chopper element 5. In powering operation,
When the on period of the chopper element 4 is t ₁ and the on / off cycle is T (constant), the on-duty ratio α becomes α = t ₁ / T (1), the input voltage is V _i , and the output voltage is Assuming V _c , there is a relationship of V _c = α · V _i (2). Further, in the regenerative operation, when the on-duty ratio of the chopper element 5 is similarly considered, there is a relation of V _c = (1−α) · V _i (3), and the output voltage V _c is the duty ratio in both cases. Tee ratio α
Can be adjusted by controlling.

When the load motor 9 is operated, the chopper device supplies power to the motor during power running, and the power is returned from the motor to the chopper device during deceleration regeneration, and the input capacitor 3 is It is charged and the voltage V _i rises. When the voltage V _i exceeds the constant value V _ON , the output of the hysteresis comparator 20 is turned on, the deceleration switch 10 is turned on, and the charge of the input capacitor 3 is discharged through the deceleration resistor 11. Although the voltage V _i decreases with the discharge, when the value becomes smaller than the constant value V _OFF , the output of the comparator 20 turns off and the deceleration switch 10 turns off. In this way, the deceleration switch 10
Each time it is turned off, the chopper input voltage V _i repeats rising / falling.

[0008]

In the above-mentioned conventional device, the output voltage V _c is controlled by controlling the duty ratio α using the chopper element, but as shown in the equations (2) and (3). If the input voltage V _i is affected by the input voltage V _{i and} changes in a cycle earlier than the response time of the voltage control system, there is a problem that the input voltage V _i is directly affected by the change.

The present invention has been made in order to solve the above problems, and an object of the present invention is to reduce the fluctuation of the output voltage V _c even when the input voltage V _i fluctuates, and to perform a stable operation. To provide a device.

[0010]

In order to achieve the above object, the present invention provides a voltage reference in a chopper device for adjusting the output voltage by on / off controlling a switch element provided between a DC power source and a load. And a voltage control means for controlling an on / off duty ratio of the switch element according to a deviation between the output voltage and the output voltage, and the on / duty ratio is inversely proportional to the input voltage of the switch element. A correction means for controlling the temperature is provided.

[0011]

With the correction means, the on-duty ratio is corrected so as to be inversely proportional to the input voltage, and the influence of fluctuations in the input voltage is eliminated and stable voltage control can be performed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, the elements with the same numbers as those in FIG.

The divider 22 outputs the output value E _{c of the} voltage controlled amplifier 16.
Is divided by the detection value V _i of the voltage detector 19 to output a value, which is a part newly provided in the present invention. The divider output value of the voltage control amplifier 16 by 22 E _c is x = K / V _i (where, K is a constant) (4) only is corrected. By this correction, the influence of the input voltage V _i , which has been a disturbance of the voltage control system, is removed, and the on-duty ratio is corrected according to the fluctuation of the input voltage V _i regardless of the response characteristic of the voltage control amplifier 16. Thus, stable voltage control can be performed.

In the above description, an example of an analog circuit is shown, but it goes without saying that the same effect can be obtained even if a similar function is provided by a digital circuit using a microcomputer.

[0015]

According to the present invention, even if the input side voltage of the chopper device rises due to the regenerative power of the electric motor or the input side voltage of the chopper device changes due to the voltage fluctuation of the AC power supply, the fluctuation is responded to. It is possible to obtain a chopper device in which the control amount is corrected and the fluctuation of the output voltage is suppressed and stable voltage control can be performed.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of a chopper device of the present invention.

FIG. 2 is a circuit configuration diagram of a conventional chopper device.

[Explanation of symbols]

1 ... AC voltage source 2 ... Rectifier 3 ... Input capacitor 4, 5 ... Chopper element 6 ... DC reactor 7 ... Output capacitor 8 ... Load input switch 9 ... Load (motor) 10 ... Deceleration switch 11 ... DB resistance 12 ... DIO- Insulation voltage detector 14 Voltage reference setting device 16 Voltage control amplifier 17 Pulse generator 18 Pulse amplifier 20 Hysteresis comparator 21 Power amplifier 22 Divider

Claims (1)

[Claims] 1. A chopper device for adjusting an output voltage by on / off controlling a switch element provided between a direct current power source and a load, wherein the switch element is turned on according to a deviation between a voltage reference and the output voltage. A chopper device comprising a voltage control means for controlling an off duty ratio and a correction means for controlling an on duty ratio to be inversely proportional to an input voltage of the switch element ..