JPH0132413Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit that digitally compensates for the offset value of a circuit capable of supplying a desired voltage or current to a load circuit.

For a voltmeter, the voltmeter reading or output signal when the input side is shorted is the offset value, and for an ammeter, the ammeter reading or output signal when the output side is open is the offset value. be. Various techniques are known for circuits that individually compensate for or eliminate the offset values of these voltmeters and ammeters.

However, in a device that incorporates a voltage source, a current source, a voltmeter, and an ammeter as one device, there is no known circuit that compensates for or removes (hereinafter simply referred to as compensation) the offset values of these four parts. .

The figure shows the voltage and offset compensation function according to the present invention.
FIG. 3 is a block diagram of a current control circuit. A command signal indicating a desired voltage or current to be supplied to the load circuit 14 (for example, a semiconductor element) is applied to the input terminal 1. Reference numeral 2 denotes a control circuit, for example a microprocessor, which supplies a voltage or current control signal corresponding to a command signal to the variable voltage and current generation circuit 3.
The output signal of generation circuit 3 is supplied to load circuit 14 via power amplifier 6 and current detection resistor 7. The voltage of the load circuit 14 is fed back to the input side of the power amplifier 6 via the voltage follower 11 and the amplifier 12, and the voltage of the load circuit 14 is controlled to a desired value. Therefore, the input terminal 1 is connected to the load circuit 14.
A voltage is supplied according to a command signal applied to. At the same time, the current flowing through the load circuit 14 is detected by the current detection resistor 7, converted into a voltage, and fed back to the input side of the power amplifier 6 via the amplifiers 8 and 9. That is, the amplifiers 11 and 12 cause the voltmeter 1 to
3, the amplifiers 8 and 9 and the resistor 7 constitute an ammeter 10, and the voltage and current of the load circuit 14 are controlled or monitored by the voltmeter 13 and the ammeter 10. When supplying a desired voltage to the load circuit 14,
That is, in the voltage control system, a voltage command signal is applied to input terminal 1, and load circuit 1 is detected by voltmeter 13.
4 is controlled to a desired value, and the ammeter 1
0 monitors the load current. On the other hand, in the current control system that supplies a desired current to the load circuit 14, a current command signal is applied to the input terminal 1, the current in the load circuit 14 is controlled to a desired value by the ammeter 10, and the load voltage is It is monitored by a voltmeter 13. In other words, this circuit has the ability to operate with a voltage source/ammeter or a current source/voltmeter.
The details of this circuit are described in Japanese Unexamined Patent Publication No. 121812 of 1982, which was previously filed by the present applicant.

Next, the offset compensation function of this circuit will be explained. A switch 15 is connected between the output terminal 17 and the load circuit 14, and a switch 16 is connected between the output terminal 17 and the reference point. Furthermore, switch 1
A resistor may be connected in series with 6. Voltmeter 1
3. The output signal of the ammeter 10 is applied to a memory (for example, RAM) 5 via an analog-to-digital converter 4 and is stored therein. These values are supplied to the control circuit 2 in response to a control signal from the control circuit 2. The control circuit 2 receives a command signal and an output signal from the memory 5 corresponding to the command signal, processes both signals, and supplies a control signal to the generation circuit 3. Further, a display signal is supplied to the display devices 18 and 19 to display the voltage and current of the load circuit 14.

Next, the offset compensation operations of the voltmeter, voltage source, ammeter, and current source will be explained. Note that during the offset compensation operation, the switch 15 is turned off.

(1) Offset compensation switch 16 of voltmeter 13 is turned on. That is, voltmeter 13
The input side of is shot. Voltmeter 1 at that time
The output signal of No. 3 is A/D converted and stored in the memory 5. Here, if this offset value is V ₁ and the output voltage of the voltmeter 13 in actual control is V _M , then the value (V _M - V ₁ ) is processed by the memory 5 and the control circuit 2, and is the offset compensated value. measured and displayed as

(2) Offset compensation of voltage source 3 This compensation means compensating for the difference between the voltage command signal applied to input terminal 1 and the output signal actually output from voltage source 3 at that time. . For example, when a 3 volt output command signal is applied to input terminal 1, the output of voltage source 3 is connected to load circuit 1.
This is the case when no signal is sent to supply 3 volts to 4. Switch 16 is turned off. Then, for example, a 0 volt command signal is supplied to input terminal 1. The output voltage of the voltmeter 13 at this time is A/D converted and stored in the memory 5. If this output voltage is _V2 , _V2 is the sum of the offset value _V3 of the voltage source 3 itself and the offset value _V1 of the voltmeter 13 mentioned above. V ₂ =V ₃ +V ₁ , so V ₃ =V ₂ −V ₁ . Therefore, in the subsequent actual control, for example, A
When supplying volts to the load circuit 14, the control circuit 2 responds to the A volt command signal to supply A-
A control signal corresponding to (V ₂ -V ₁ ) volts is supplied to the generating circuit 3. Note that a plurality of voltage command signals may be supplied to the control circuit 2, output signals of the respective voltmeters 13 may be obtained, and the compensation operation may be performed in an interpolative manner.

(3) Offset compensation of ammeter 10 Switch 16 is turned off. The output signal of the ammeter 10 at this time is A/D converted and stored in the memory 5. If this offset value is I ₁ and the output signal of ammeter 10 in actual control is I _M , then
The value ( _IM − I ₁ ) is compensated in the same way as (1).

(4) Offset compensation switch 16 of current source 3 is turned on. Then, a 0 ampere command signal is supplied to input terminal 1. At this time, the output signal of the ammeter 10 is A/D converted and the memory 5
stored inside. If this output signal is I ₂ , then I ₂
is the sum of the offset value _I3 of the voltage source 3 itself and the offset value _I1 of the aforementioned ammeter, and _I3 = _I2 - _I1 .
Therefore, in the subsequent actual control, for example, B
When supplying amperes to the load circuit 14, the control circuit 2 supplies a control signal corresponding to B-(I ₂ -I ₁ ) amperes to the generating circuit 3.

As is clear from the above explanation, all offsets of the voltmeter, voltage source, ammeter, and current source are effectively compensated, and the load circuit 14 is supplied with accurate voltage and current corresponding to the command signal. , the voltage and current of the load circuit 14 can be accurately measured.

[Brief explanation of the drawing]

The figure shows the voltage with offset compensation function according to the present invention.
FIG. 3 is a block diagram of a current control circuit. 2: Control circuit, 3: Variable voltage and current generation circuit, 4: Analog-to-digital converter, 5: Memory, 6: Power amplifier, 10: Ammeter, 13: Voltmeter, 14: Load circuit.

Claims (1)

[Scope of utility model registration request] a voltage source and a current source that generate variable voltage and current corresponding to a control signal, means for supplying output signals of the voltage source and current source to a load circuit via a power amplifier and a current sensing resistor, and the current sensing device. It consists of an ammeter that detects the voltage between both terminals of the resistor and supplies a feedback signal to the input side of the power amplifier, and a voltmeter that detects the load voltage and supplies a feedback signal to the input side of the power amplifier. , in a circuit that supplies desired voltage and current to the load circuit corresponding to the control signal, a switch that opens or shorts an output terminal to which the load circuit is connected; and a switch that controls the current when the switch is turned on or off. a memory circuit that converts the output signals of the meter and voltmeter from analog to digital and stores the output signals as offset values of the voltage source, current source, voltmeter, and ammeter; or receiving a command signal indicating a current and an output signal representing an offset value in the memory circuit corresponding to the command signal;
A voltage/current control circuit with an offset compensation function, comprising a control circuit that generates the control signal.