JPH03183357A - Chopper controller - Google Patents

Abstract

PURPOSE:To produce a stabilized output voltage, which is not subjected to an abrupt variation of input voltage, by providing a feedforward circuit for controlling the input voltage. CONSTITUTION:A feedforward circuit 31 is interposed between a voltage control circuit 3 and an input voltage detecting circuit 4. A main control circuit 2 interrupts base signal of a transistor 8 if abnormal I/O voltages and output current are detected based on the outputs from in input voltage detector 4, an output voltage detector 6 and an output current detector 7. The main control circuit 2 also provides a voltage, controlled through the feedforward circuit 31, to a section for comparing a voltage designated at the voltage command section 1 for the voltage control circuit 3 with a voltage detected through the output voltage detector 6, thus correcting the output from the voltage control circuit 3. Furthermore, base signal of the transistor 8 is controlled based on the value of DC current detected through the output current detector 7.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a chopper control device that controls the output voltage from a chopper element so that it becomes equal to a voltage command value. Figure 2 is a circuit diagram showing a conventional chopper control device.
In the figure, 2 is a voltage command unit consisting of a variable resistor, etc.
3 is a main control circuit, 3 is a voltage control circuit that controls the output voltage of the chopper element, 4 is an input voltage detector that detects the input voltage to the chopper element, 5 is a base amplifier that jumps the transistor 8 as the chopper element, 6 1 is an output voltage detector that detects the output voltage after smoothing, 7 is an output current detector that detects the output current of the chopper element, 9 is a freewheel diode, 10 is a smoothing reactor, and 11 is a smoothing circuit 12 together with the smoothing reactor 10. This is a smoothing capacitor. Further, the transistor 8 as a chopper element constitutes a chopper circuit that converts a DC voltage into a pulsed voltage.

Next, the operation will be explained. First, input terminal P, P2
When a DC voltage of a predetermined level is applied to.

The transistor 8 is turned on/off by a control signal input from the voltage control circuit 3 through the pace amplifier 5, chops the DC voltage, and outputs a pulsed voltage. Moreover, this pulsed voltage is applied to the smoothing reactor 10.
and a smoothing circuit consisting of a smoothing capacitor 11, and the input terminal P3. It is output as a DC voltage at a predetermined level to P4. In this case, the main control circuit 2 includes an input voltage detector 4. If there is an abnormality such as overvoltage or overcurrent in the input/output DC voltage and output DC current detected by the output voltage detector 6 and output current detector 7, this is detected and the base signal to the transistor 8 is cut off. Also,
The voltage control circuit 3 adjusts the base signal of the transistor 8 so that the voltage specified by the voltage command unit 1 becomes equal to the voltage value detected by the output voltage detector 6, and also based on the DC current detected by the output current detector 7. control. At this time, the base amplifier 5 outputs a control signal to turn on/off the transistor 8 as a chopper element based on the output of the voltage control circuit 3. Note that current flows through the freewheel diode 9 when the transistor 8 is turned off. The pulsed voltage thus obtained is smoothed by the smoothing reactor 1o and the smoothing capacitor 11 to output a DC voltage at a predetermined level with less pulsation.

[Problem to be solved by the invention]

Since the conventional chopper control device is configured as described above, a sufficiently stable output voltage of the transistor 8 can be obtained even when the DC input voltage fluctuates slowly, but when the DC input voltage suddenly fluctuates, Since the output voltage of the base amplifier 5 is controlled by detecting fluctuations in the output voltage obtained through the transistor 8 as a chopper element, the fluctuations in the output voltage of the transistor 8 become large, making it difficult to obtain a stable DC output. There were some issues, such as not having one.

In addition, as a prior art, semiconductor power conversion circuits (IEEJ 1
Published March 31, 1987) P, 65-P.

There is one published in 71 by M.

This invention was made to solve the above problems, and provides a chopper control device that can stably output an output voltage even when the input voltage of a chopper element such as a transistor fluctuates rapidly. The purpose is to

[Means to solve the problem]

The chopper control device according to the present invention includes a feedforward circuit that controls the input voltage input to the chopper element in addition to the conventional voltage control circuit, thereby controlling the input voltage and outputting it from the chopper element in the voltage control circuit. The output voltage is input to the comparator between the output voltage and the command voltage to correct the output of the voltage control circuit and turn on/off the chopper element.
It is designed to be turned off.

[Effect]

The feedforward circuit in this invention detects and controls fluctuations in the input voltage to the chopper element and inputs the detected voltage to the voltage control circuit, thereby correcting the fluctuations before the output voltage of the chopper element fluctuates. To obtain stable DC output even when the current fluctuates.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

In Figure ↓, 31 is a feedforward circuit that controls the voltage value detected by the input voltage detector 4, and this is connected between the voltage control circuit 3 and the input voltage detector 4. Note that other circuit parts that are the same as those shown in FIG. 2 are designated by the same reference numerals, and redundant explanation thereof will be omitted.

Next, the operation will be explained. First, the main control circuit 2 has an input voltage detector 4. If there is an abnormality such as overvoltage or overcurrent in the input/output DC voltage and output DC current of the transistor 8 as a chopper element detected by the output voltage detector 6 and output current detector 7, the base signal of the transistor 8 is detected. Cut off.

Further, the voltage control circuit 3 makes the voltage specified by the voltage command unit l equal to the voltage detected by the output voltage detector 6, and also adjusts the voltage value controlled by the feedforward circuit 31 to the voltage in the voltage control circuit 3. The voltage specified by the command unit l and the voltage detected by the output voltage detector 6 are inputted to a comparison unit, the output of the voltage control circuit 3 is corrected, and based on the above DC current detected by the output current detector 7, The base signal of the transistor 8 is controlled. That is, based on the output of the voltage control circuit 3, the base amplifier 5 turns on/off the transistor 8 to output a stable output voltage.

Furthermore, current flows through the freewheel diode 9 when the transistor 8 is turned off. In this way, the pulsed voltage obtained from the transistor 8 is smoothed and outputted by the smoothing reactor 10 and the smoothing capacitor 1, making it possible to obtain a stable DC output voltage even in the face of rapidly changing input DC voltage. can.

Note that although the two-legged embodiment uses the transistor 8 as the chopper element, a switch element such as a gate turn-off thyristor may also be used.

〔Effect of the invention〕

As described above, according to the present invention, a feedforward circuit is provided to control the input voltage input to the chopper element, and the input voltage is controlled by the feedforward circuit and input to the voltage control circuit to correct the output of the voltage control circuit. Since the chopper element is configured to be controlled on/off, it is possible to obtain a device that can always output a stable output voltage even if the input voltage to the chopper element fluctuates rapidly.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a chopper control device according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing a conventional chopper control device. 3 is a voltage control circuit, 8 is a chopper element (transistor)
, 12 is a smoothing circuit, and 31 is a feedforward circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Diagram: 117 elements

Claims (1)

[Claims] a chopper element that chops a DC input voltage and converts it into a pulsed output voltage; a smoothing circuit that smoothes the output voltage from the chopper element; A chopper control device comprising a voltage control circuit that controls on/off the chopper element based on the output current from the element,
A feedforward circuit is provided which controls the input voltage, inputs the controlled input voltage into a comparison section between the output voltage and the command voltage in the voltage control circuit, and corrects the output of the voltage control circuit. Characteristic chopper control device.