JPH0753430Y2 - Power converter controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a control device for a power converter in which a main circuit current varies over a wide range.

[Conventional technology]

When the input current changes over a wide range, the current detector changes its detection accuracy between a large current and a small current. For example, in the case of a current detector using a Hall element, its rating is represented by the product of the value of the current flowing through the Hall element and the number of turns (the number of turns) of the detection winding, or ampere-turn (AT).
If the number of turns is reduced in order to make it possible to measure a large current range, the detection accuracy will decrease when measuring a small current range.

FIG. 3 shows electric power in an acceleration tester for carrying out an operation confirmation test of an acceleration sensor for detecting the operation timing of an airbag in an airbag unit mounted in an automobile or the like and used for lifesaving in the event of a vehicle collision. It shows a converter.

In FIG. 3, 11 is a single-phase AC power supply, 12 is a rectifier, and 13
Is an electrolytic capacitor, 14 is an inverter, and is composed of four power transistors T _R1 , T _R2 , T _R3 , and T _R4 that are bridge-connected, and a mover (armature coil) 1 between its AC output terminals A and B. Is inserted. D is a flywheel diede. 3 is the above-mentioned acceleration sensor which is a test piece, and 15 is a current detector (DCCT).

Reference numeral 16 is a commander, 17 is a controller for the inverter, and has a PWM signal generation circuit 18 and a base drive circuit 19, and the base drive circuit 19 sends the base drive signal to the transistor T of the inverter 14.
Supply to _{R1 to} T _R4 . 20 is a PI integration circuit, 21 is a carrier wave generation circuit, 22 is a comparison circuit, and 23 is an isolation amplifier. A field power supply device 24 is a rectifier device in which a controllable rectifying element Sh is bridge-connected and a phase is controlled. A gate signal is supplied from a gate controller 25, and a field current is supplied to a stator (field coil) 2. Supply.

Command unit 16 is a microcomputer CPU, an input device given the test acceleration g and other parameters through (not shown) stored in a memory (not shown), calculates a current command (acceleration command P _g and braking command P _s) Then, it is transmitted at a predetermined sampling interval T _s . The acceleration command P _g has a harbor sine waveform as shown in FIG. 4 and has a time width T = 10 to 20 ms.
Signal.

In this configuration, when the command device 16 sends the acceleration command P _g , the PWM signal generation circuit 18 compares the output of the PI integration circuit 20 which inputs the deviation between this and the feedback current with the carrier wave (for example, carrier frequency 6 KHz). To create a PWM signal. The base drive circuit 19 generates a base drive signal based on this PWM signal and supplies it to the bases of the transistors _TR1 and _TR4 .
As a result, both transistors T _R1 and T _{R4 turn} ON / OFF at the same time.
The switching current is started, and a drive current (maximum value, for example, 300 amperes) I _a whose envelope waveform is similar to the envelope waveform of the acceleration command P _g is supplied to the mover 1, and the mover 1 is rapidly accelerated to a predetermined level. The collision acceleration g is reached. During braking, the inverter controller 17 sends a base drive signal to the transistor T _R2 and T _R3, starts the switching operation both transistors T _R2 and T _R3 is ON / OFF simultaneously. As a result, the mover 1
, A braking current I _s having a polarity opposite to that of the driving current I _a flows, and the movable element 1 stops braking.

[Problems to be solved by the device]

When performing current feedback control of the power converter whose output current changes in a wide range in this way, one current detector with a large detection range is used for current detection. Since the detection accuracy is lowered and the control accuracy of the power converter is lowered, in order to prevent this, the applicant of the present invention, as shown in FIG. 5, uses one current detector (DCCT).
We proposed a system in which the output lines 26A and 26B of the two systems with different numbers of turns are pierced and the two systems are switched by the contactor 27 according to the load region (Japanese Patent Application No. 1-333155).

However, this method is not suitable for applications in which the switching frequency is high due to the use of the contactor 27, and the switching time is large, for example, 100 msec, so that the level is as high as the output current of the power converter. There is a problem that it cannot be applied to applications that change and require quick control.

This invention was made to solve the above problems,
Even if the feedback current changes in a wide area and at high speed, it is possible to prevent fluctuations in control accuracy due to the detection accuracy of the current detector and to perform stable and highly accurate control in a wide current range. An object is to provide a control device for a converter.

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides at least two current detectors having the same rating but different number of turns of the detection windings as current detection means for detecting and feeding back the main circuit current of the power converter. Selecting means for selecting the feedback gain of the current detecting means in accordance with the load current region. In claim 2, the output means of each current detector has a control system which is fed back, and the selecting means has the load current. The output of the corresponding control system is selected according to the region, and in the claim 3, the selecting means selects either the output of one current detector or the sum of the outputs of both current detectors, depending on the load current region. Is configured to be selected.

[Action]

In this device, at least two current detectors are provided,
In the current region where the detection accuracy of one current detector decreases,
Since the other current detector is selected and the feedback gain is increased, a decrease in the feedback current detection accuracy is prevented.

〔Example〕

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

In FIG. 1, 15A and 15B are current detectors (DCCT) using Hall elements, both of which are provided in series with the output circuit of the inverter 14. Current detector 15A is the detection winding 1
Turn (current rating 1000AT) current transformer, current detector 15B
Is a current transformer with 3 turns of detection winding (rated 1000AT).

18A is the first PWM signal generating circuit, which is the current detector 15A
The deviation between the feedback current I _fA sent by and the output from the command unit 16 is input. 18B is a second PWM signal generating circuit is input the deviation between the output from the feedback current I _fB and command unit 16 that the current detector 15B is sent. 30
Is a switching logic, which receives the switching signal S sent from the judging circuit 31 and, when the switching signal S is at level H, sends the PWM signal sent from the first PWM signal generating circuit 18A to the base drive circuit 19. If the level is L, then the second
The PWM signal generated by the PWM signal generation circuit 18B is transmitted to the base drive circuit 19. The judgment circuit 31 is the output current of the inverter 14.
When the output of the current detector 32 that detects I _a is taken in and the value is larger than the set value I _K in absolute value, the level H
Of the switching signal S of level L
Is sent.

In this configuration, when the inverter output current I _a is in the large current region where I _a > I _K , the switching signal S of level H is input to the switching logic 30, so that the PWM signal generating circuit 18A outputs the PWM signal. The signal is supplied to the base drive circuit 19. I _a <I _K
In the small current region, the switching signal S of level L is input to the switching logic 30, so that the PWM signal sent from the PWM signal generating circuit 18B is supplied to the base drive circuit 19.

As described above, in this embodiment, two feedback control systems are provided, one of which is the current detector 15 having a large detection range.
The current feedback is performed through A, and the other current feedback is performed through the current detector 15B having a small detection range, and both systems are switched depending on the magnitude of the inverter output current I _a , so that the feedback gain in the small current range is increased. In the case of the example, up to about 1000/3 = 300 A, the detection accuracy of the current detection value can be three times higher than the conventional one.

Further, in this embodiment, the PWM signal is switched, but since the control signal level is switched, high speed / high frequency switching is possible.

FIG. 2 shows another embodiment of the present invention, which uses a one-turn current detector (1000T) 15A and a two-turn current detector (1000AT) 15C, and when I _A <I _K , Feedback control is performed with the value obtained by adding the outputs I _fA and I _fC of both current detectors in the adder 33 as feedback current value, and I _a > I _K
In the range of, by closing the switch 34, it has a configuration for performing feedback control only the output I _fA of the current detector 15A as feedback current.

In this embodiment, the one-turn current detector 15A is selected in the large current region, but both the one-turn and two-turn current detectors 15A and 15B are selected in the small current region. Similar to the above case, up to about 300 A, it is possible to obtain the detection accuracy three times higher than the conventional one.

Since the switch 34 in this embodiment also switches the signal level, high speed / high frequency switching is possible.

In each of the above embodiments, the current detectors 15A and 15B are automatically switched, but it goes without saying that they may be manually switched.

In each of the above embodiments, two current detectors are used, but if three or more current detectors having the same rating but different number of turns of the detection winding are used, the detection accuracy can be made more constant. In addition, the accuracy can be made higher.

Further, although the current detector in each of the above embodiments uses the Hall element, the present invention is not limited to this type of current detector.

Further, in each of the above-described embodiments, an example in which the present invention is applied to a power converter for an acceleration tester has been described, but the present invention is applied to other uses and power converters of other methods to obtain the same effect. be able to.

[Effect of device]

As described above, this invention has a configuration in which at least two current detectors are provided and the other current detector is selected to increase the feedback gain in the current region where the detection accuracy of one current detector is reduced. As a result, over the entire current range,
Since it is possible to obtain the desired detection accuracy,
It is possible to perform stable and highly accurate current feedback control over a wider current region.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing another embodiment of the present invention, FIG. 3 is a circuit diagram showing an example of a power converter, and FIG. 4 is an inverter. Output current 1
FIG. 5 shows an example, and FIG. 5 is a circuit diagram showing a conventional current detecting means. 1 ... Mover, 2 ... Stator, 14 ... Inverter, 15
A, 15B, 15C ... Current detector, 17 ... Inverter controller, 18, 18A, 18B ... PWM signal generation circuit, 19 ... Base drive circuit, 30 ... Switching logic, 31 ... Judgment circuit, 32 …
… Current detector, 34… Switch.

Claims (3)

[Scope of utility model registration request] 1. In a control device for a power converter that performs current feedback control, current detection means for detecting and feeding back the main circuit current of the power converter has the same rating, but the number of turns of the detection winding is different. A control device for a power converter, comprising at least two current detectors, and having selection means for selecting a feedback gain of the current detection means according to a load current region. 2. A control system for feeding back the output of each current detector, and the selecting means selects the output of the corresponding control system according to the load current region.
A control device for the power converter described. 3. The power converter according to claim 1, wherein the selecting means selects either the output of one of the current detectors or the sum of the outputs of both current detectors in accordance with the load current region. Control device.