JP2560375Y2 - Power regeneration device - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention comprises a converter in which a bridge-connected diode is connected in reverse parallel with a regenerative switching element, and a smoothing capacitor inserted between the load-side positive and negative terminals of the converter. The present invention relates to a power regeneration device that controls this switching element with a conduction command signal having a predetermined width.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional example of a power regeneration device. In the figure, 1 is a three-phase AC power supply, 2 is a reactor, 3 is a converter, 4 is a capacitor for smoothing,
5 is an inverter, and 6 is a load such as a motor. Converter 3, each of the bridge-connected diodes D ₁ to D _6, the transistor T _r1 through T _r6 for regeneration have antiparallel-connected circuit arrangement. 7 is a transformer, 3
The three-phase AC voltage having the same phase as the _AC voltage VAC of the phase AC power supply 1 is stepped down and taken out, and supplied to the 120 ° conduction command signal generation circuit 8. 9 is a base drive circuit of the transistor T _r1 through T _r6.

FIG. 3A shows an output waveform of the converter 3 during regeneration.

[0004] In this configuration, when the voltage of the capacitor 4 and V _DC, if it is 1.35V _AC> V _DC, the diode D ₁ of the AC power source 1 → reactor → converter 3
ＤD ₆ → capacitor 4 → inverter 5 → load 6 The load current _IL flows through the path, and the capacitor 4 is charged. Conversely, at a 1.35V _AC <V _DC, regenerative current I flows through a path of the transistor T _r1 through T _r6 → reactor → the AC power supply 1 of the capacitor 4 → converter 3. 1.35V _AC = V
_In the case of _DC , neither the load current _IL nor the regenerative current I flows.

[0005]

As described above, in the above-mentioned electric power regenerating apparatus, the switching from the power running operation to the regenerative operation, and vice versa, is automatically performed without giving a switching command or the like. as is only controls the transistor T _r1 through T _r6, since not performed the voltage controlled current also control, but requires only a simple circuit configuration, even if the flow is large anomalous current for some reason, to suppress this Not be able to
If a power failure occurs in the three-phase AC power supply 1 during the power running operation, 1.35 V _AC <V _DC , so that the regenerative operation is performed. In some cases, the voltage V _{DC of the} capacitor 4 is 0.
The situation that becomes becomes.

The present invention has been made to solve this problem, and provides an electric power regenerating apparatus which can prevent overcurrent and malfunction and can improve reliability without deteriorating the advantages of the prior art. The purpose is to do.

[0007]

In order to achieve the above object, according to the present invention, a current of a main circuit is detected, and when the detected value exceeds a current set value, a switching element of a converter is detected. Is PWM-controlled.

According to a second aspect of the present invention, the voltage of the smoothing capacitor is detected, and when the detected value exceeds the regenerative level set value, the switching element of the converter is driven.

[0009]

According to the present invention, during normal regenerative operation, the switching element of the converter is controlled at a constant conduction angle of 120 °, and when the regenerative current exceeds the set value giving the current upper limit value, the conduction angle becomes the excess current amount. You will be able to squeeze a considerable amount.

Further, even when a power failure occurs during power running and the AC voltage is lost, current does not flow through the path of the capacitor, the switching element of the converter, the reactor, and the AC power supply 1.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 11 denotes a current detector CT, which is inserted between the reactor 2 and the converter 3. An alternating current output from the current detector CT is converted into a direct current by a full-wave rectifier 12. You. Reference numeral 13 denotes a current upper limit setting device which outputs a current upper limit value _IMAX . 14 is a current computing unit, based on the deviation ΔI of feedback current I _F and the current limit I _MAX that the full-wave rectifier 12 outputs, for generating a signal below.

[0013] When the _{(A) ΔI = I MAX -I} F> 0 in magnitude proportional to [Delta] I, in the case of the voltage V _C-MIN following signals _{(B) ΔI = I MAX -I} F <0 to [Delta] I Proportionally larger than V _C-MIN , V
Generates a signal smaller than _C-MAX . Here, V _C-MIN is the minimum value of the triangular wave V _C output by the triangular wave generator 15, V _C-MAX is the maximum value of the triangular wave V _C. The comparator 16 compares the triangular wave V _C with the output of the current calculator 14, and when the above case (A) is satisfied,
An H level constant level signal V _K is generated, and in the case of (B), a PWM signal V _PWM is generated. Reference numeral 17 denotes a gate circuit (AND circuit), from which the output of the comparator 16 and the output Vα _{120 of the} 120 ° conduction command signal generating circuit 8 are led, and the output of the gate circuit 17 is supplied to the base drive circuit 9.

[0014] Thus, in this embodiment, the regenerative state and the regenerative current I is below the current limit I _MAX is the gate signal of the gate circuit 17 is at a constant level signal V _K, each transistor T _r1 ~ _{Tr 6} is controlled to conduct at 120 °. When the regenerative current I exceeds the maximum current I _MAX, since the gate signal of the gate circuit 17 becomes a PWM signal I _PWM, each transistor T _r1 through T _r6 is PWM controlled, regenerative current I
_Is kept below the current upper limit IMAX. An example of the output waveform of the converter 3 at this time is shown in FIG.

[0015] Thus, in this embodiment, during normal regeneration operation, the transistor T _r1 through T _r6 is controlled constant conduction angle of 120 °, the abnormality of the regenerative current I exceeds the maximum current I _MAX, the conduction The angle is reduced by ΔI.

FIG. 2 shows another embodiment of the present invention. In the figure, reference numeral 18 denotes a switch, and the output of the AND circuit 17 is supplied to the base drive circuit 9 via the switch 18.

The switch 18 is controlled to open and close by the output of a comparator 19. The comparator 19 outputs the voltage _{VDC of the} capacitor 4 detected by the voltage detector 20 to the regeneration level setting unit 19.
When the regenerative level reaches the output regeneration level V _S , a closing command signal is given to the switch 18.

[0018] Thus, in this embodiment, at the regenerative state, the switch 18 is closed and, since the transistor T _r1 through T _r6 of the converter 3 becomes to be ON / OFF driving, during power running, power failure Te, also the AC voltage V _AC is lost, the transistor T _r1 of the capacitor 4 → converter 3
~ _Tr6 → reactor → AC power supply 1 does not cause current to flow.

[0019]

According to the present invention, as described above, when the magnitude of the regenerative current exceeds the upper limit value of the current, the switching element of the converter switches from the constant conduction angle control to the feedback control for reducing the total conduction time according to the amount of overcurrent. Since the switching to the switching mode, it is possible to prevent an abnormal current from flowing, and a circuit for detecting a regenerative state is provided, and the regenerative switching element is configured to operate only in the regenerative state. Even if such an occurrence occurs, malfunction can be prevented, so that reliability can be improved as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing another embodiment of the present invention.

FIG. 3 is a diagram showing an output waveform during a regenerative operation of the converter.

FIG. 4 is a block diagram showing a conventional power regeneration device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 AC power supply 2 reactor 3 converter 4 capacitor 5 inverter 6 load 7 transformer 8 120 ° conduction command signal generation circuit 9 base drive circuit 11 CT 12 full-wave rectifier 13 current upper limiter 14 current calculator 15 triangular wave generator 16 comparator 17 Gate circuit 18 Switch 19 Comparator 20 Regenerative level setting device

Claims (1)

(57) [Scope of request for utility model registration] 1. A main circuit comprising: a converter in which regenerative switching elements are connected in anti-parallel to each of the bridge-connected diodes; and a smoothing capacitor inserted between the load-side positive and negative terminals of the converter. In a power regeneration apparatus having a control circuit including a command circuit that constantly generates a conduction command signal having a predetermined width synchronized with an AC power supply, and a drive circuit that inputs the conduction command signal and drives the switching element on / off. Main circuit current
Is detected and DC converted, and the converted current value is set in advance.
If the current exceeds the specified current value , the switching element
A power regeneration device that is controlled by WM.