JPS61128792A - Power source regeneration system of voltage type inverter - Google Patents

Abstract

PURPOSE:To adapt for the use of the case of driving a load that a brake torque is smaller than a drive torque by setting a DC intermediate voltage at driving time corresponding to a diode rectifying voltage irrespective of the presence or absence of power source regeneration. CONSTITUTION:A generation brake circuit 6 is provided in a DC intermediate circuit. A power reactor 2 is controlled so that the phase delay angle of the reactor 2 is maximum at the DC intermediate circuit voltage at driving time. An inverter 3 is controlled so that the output voltage becomes equal to the maximum value. Regenerative energy is consumed by a generation brake circuit 6 at braking time to reduce the DC intermediate circuit voltage to the value capable of converting by a power inverter 2', while the inverter 3 is decreased at its output voltage to the value to regenerate the power source.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a voltage-type pulse width modulation device which is supplied with DC power through a thyristor converter device consisting of a single-pot, reverse-surge converter and operated in a manner without circulating current. This invention relates to a power regeneration method in a (PWM) inverter.

[Conventional technology]

FIG. 2 is a configuration diagram showing a conventional example of such a power regeneration system.

First, the main circuit connects a three-phase bridge rectifier circuit (thyristor converter 2j2') connected in antiparallel to a three-phase AC power supply 1, and a DC reactor 4 and a smoothing capacitor 4 on the DC side. It is connected to an inverter 3 through a filter circuit consisting of 5, and an induction machine 7 is connected to the AC side of the inverter 3.

To control the inverter 3, for example, a known frequency/velocity adaptive vector control method is adopted, and specifically, the current detection converter 10', the speed detector 8. Speed setter 37. Speed regulator (ASR) 3<Sj vector calculator 34. Current regulator (
ACFL)33. It is composed of a pulse width modulator 62, a pace drive circuit 31, and the like.

Its operation is as follows. Speed regulator (A5R) 5
6 performs a predetermined calculation to zero out the deviation between the speed setting value n1 given via the setting device 67 and the speed actual value n detected by the speed detector 8, and outputs a predetermined operation output. .

The output of person 5R56 is the torque command (torque current command lT*
) and is given to the vector arithmetic unit 34. The vector calculator 34 determines whether the torque command value < t? ” ) p detector 8
The actual speed value n detected by the magnetic flux command 1i, which is preset therein! (Φ0), the secondary side resistance value of the induction machine 7, etc., vector calculation is performed on the primary current command value (i1*) of the induction machine 7, and the deviation is output. This primary current command value (11
”) and the primary current command 1f[
The deviation from (tl) is given to the current regulator 33, which causes the current regulator 36 to output a predetermined operation output and give it to the pulse width modulator 32 in order to make this deviation zero. The pulse width modulator 32 compares the modulated wave control signal (M) given via the ACR 35 with a predetermined carrier signal (C), and outputs a predetermined on/off signal (PWM signal) according to the result. By operating predetermined transistors of the inverter 3 via the pace drive circuit 31, a predetermined three-phase AC voltage is generated and the load 7 is driven.

On the other hand, the power supply side converters 2, 2' are operated in a so-called no-circulating-current system, and for example, a voltage control system with a current minor loop is used for their control. Specifically, the current detecting current transformer 10. Rectifier 11° Voltage setting device 29. Converter switching circuit 28. Voltage regulator (human VR) 27. Current regulator (ACR) 26° phase angle generator 22. It is composed of gate pulse generators 21 and 21', etc.

Its operation is as follows. Voltage regulator (AVR) 2
7 performs a predetermined calculation to make the deviation between the set value from the voltage setter 29 and the DC intermediate voltage detection value zero, and outputs the result as a current command value. Current regulator (ACFL)
26 receives the deviation between this current command value and the actual current value obtained through the current transformer 10 and rectifier 11, and provides an output corresponding to this deviation to the phase angle generator 22 to adjust the phase control angle. The output of the phase angle generator 22 is applied to a gate pulse generator 21, 21' and is applied as a gate pulse to each transducer 2.2'. The converter switching circuit 28 is provided to switch between the forward and reverse converters 2 and 2', and for example, changes the current command direction (for example, if the output of the AVR 27 is positive, it is a drive, and if the output of the AVR 27 is negative, it is a brake). First, a pulse shift command (command to set the phase angle to the maximum delayed phase angle and reduce the current to zero) is given to the phase angle generator 22 to reduce the current, and after confirming that this current has become zero, After cutting off the gate pulse generator 21 or 21' that had been selected, select the opposite gate pulse generator 21 or 21', and then cancel the pulse shift command given to the phase angle generator 22. Converter 2°2' is switched.

In such a configuration, the power supply side converter is normally operated as a diode rectifier when there is no power regeneration, and is operated as a converter when power regeneration is performed. Each output voltage Ed at this time is expressed as in the following equation.

When used as a diode rectifier, Ed-Rdn ・-” (1
) as a converter Ea −Edo * cos α −−
----(2) where Edo is the maximum flow intermediate voltage during no control, and α is the phase delay angle. That is, when performing power regeneration, it is necessary to lower the DC intermediate circuit voltage by the cosine value of the phase delay angle α corresponding to the commutation margin angle β during regeneration, that is, cosa, than in the case without power regeneration. For this reason, conventionally, when power regeneration is required, K performs driving and braking operations by lowering the DC intermediate voltage in advance so that the power supply side inverter can commutate during regeneration.

[Problem that the invention seeks to solve]

If the above method is used, not only will the capacity of the power supply side converter not be fully utilized, but also the braking torque may be lower than the driving torque (in reality, there are many such types of loads). The problem is that it is not suitable for driving.

[Means and effects for solving the problem] This invention aims to effectively utilize the power supply side converter by allowing the DC intermediate circuit voltage to be operated at its maximum value during operation even when power regeneration is provided. be. In other words, a dynamic braking circuit is generally installed in the DC intermediate circuit, and during driving, the phase delay angle of the forward converter is adjusted so that the DC intermediate circuit voltage is maximized.
While performing this control, the inverter also controls its output voltage to be equal to this maximum voltage, and during braking, the above-mentioned dynamic braking circuit consumes regenerative energy to reduce the DC intermediate circuit voltage to a value that can be commutated by the inverter. At the same time, the inverter also lowers its output voltage to just this point to regenerate power.

〔Example〕

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

This is clear if you compare it with Figure 2. Is there a smoothing capacitor in the DC intermediate circuit in the main circuit? 5 is connected in parallel with the dynamic braking circuit 6, and the inverter control circuit is connected to the output of the ASR 36, that is, the torque command, to the torque command switching circuit 35f:
A predetermined command for lowering the motor excitation current is given to the vector calculator 34 during braking, and a transformer 9. is used for detecting drive/brake mode. It is characterized by the addition of a rectifier 11 and a voltage comparator 12, as well as the provision of a control circuit 16 for switching drive/braking modes. In addition,
The thyristor converters 2, 2' are connected to the phase angle setter 2.
The difference is that the DC intermediate voltage is generated by controlling with the fixed phase angle set in 4.24', but this is not essential, and it is the same voltage constant control with current minor loop as in Fig. 2. There are many things you can do as well.

Further, the current limit adjuster 23 and the current limit setter 25 are provided to suppress overcurrents generated due to various causes.

Here, the switching operation from drive mode to braking mode will be explained.

First, when the control circuit 1i 113 determines that it is in the braking mode from the inverter torque command direction which is the output of the As FL56 and the motor rotation direction determined by the detector 8, it gives a zero torque command to the vector calculator 34 (torque command While operating the switching circuit 35 and giving a command to the vector calculator 34 to lower the motor voltage, that is, to lower the excitation current, a pulse shift command is given to the phase angle generator 22, 22' of the thyristor converter control circuit. In order to make the converter current zero, the gate circuits 21 and 21' are cut off, and the dynamic braking circuit 6 is driven so that the energy of the capacitor 5 is consumed by the resistor provided in the dynamic braking circuit 6. Lowers the capacitor voltage. Therefore, the dynamic braking circuit 6 is composed of a series circuit of at least a resistor and a switching element.The capacitor voltage (DC intermediate circuit voltage) is set in advance by the opposite phase angle setting device 24'. When the voltage comparator 12 detects that the voltage corresponds to the phase angle, that is, the voltage that allows commutation, the dynamic braking circuit 6 is cut off, and the pulse cutoff signal to the gate pulse generator 21' is released. , the pulse shift command to the phase angle generators 22, 22' is canceled and power regenerative braking is started.At the same time, the zero torque command to the torque command switching circuit 55 is also canceled and regenerative braking by the inverter is performed.

〔effect〕

According to this invention, since the DC intermediate voltage Ed during driving is set to Ed = Eda, that is, equivalent to the diode rectified voltage, regardless of whether power regeneration is performed or not, the motor voltage can be set to a voltage corresponding to this, and the power supply side This provides the advantage that the converter can be used more effectively. Therefore, the present invention is suitable for use when driving a load where the braking torque is smaller than the driving torque. Note that the new dynamic braking circuit provided by this invention only needs to consume at most 10% of the energy possessed by the capacitor within a short period of time during regeneration, so the burden caused by its provision is The increase can be almost ignored.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. Description of symbols 1... AC power supply, 2, 2'... Thyristor converter, 6... Inverter, 4...
・DC reactor, 5...Smooth; Nde/su, 6
......Dynamic braking circuit, 7...Induction motor, 8...Speed detector, 10, 10'...
・AC current transformer, 11... Rectifier, 12...
...Comparator, 13...--Control circuit, 21.21'
......Gate pulse generator, 22, 22'...
... Phase angle generator, 23 ... Current limit adjuster, 24.24' ... Phase angle (α, β) setting device,
25...Current limit value setter, 26.55...
...Current regulator (ACR), 27...Voltage regulator (AVR), 28...Converter switching circuit, 2
9... Voltage setting device, 31... Base drive circuit, 32... PWM modulator, 34...
...Vector calculator, 35...-Torque command switching circuit, 66...Speed regulator (person SR), 37...
−・・−・Speed setting device.

Claims (1)

[Claims] In a voltage source inverter that is supplied with DC power through a converter that consists of forward and reverse converters and is operated without circulating current, a dynamic braking circuit is provided in the DC intermediate circuit, and when driving, the phase delay angle of the forward converter is is controlled so that the DC intermediate circuit voltage becomes maximum, while the inverter is also controlled so that its output voltage becomes equal to the maximum value, and during braking, the regenerative braking circuit consumes regenerative energy to reduce the DC intermediate circuit voltage. A power regeneration system for a voltage type inverter, characterized in that the intermediate circuit voltage is lowered to a value that allows the inverter to commutate, and the inverter also lowers its output voltage to a voltage that allows commutation to perform power regeneration.