JPS6118379A - Controlling method of bidirectional power rectifier - Google Patents

Abstract

PURPOSE:To simplify a control circuit and to improve the controlling performance by using the phase voltage of an AC power source as the upper limit command of the regenerative current as it is to obtain a deviation from the regenerative current, and using it as regenerative control signal. CONSTITUTION:In a bidirectional power rectifier having a rectifier bridge 1, a self-extinguishing switch element 2 and a smoothing capacitor 3, a phase voltage detector 4 and a current detector 5 are provided at the AC power source side of the bridge 1 to obtain a deviation between the phase voltage detected value and the regenerative current detected value. This deviation is amplified by a current regulator 6, compared by a comparator 8 with the output of a carrier signal generator 7 to obtain a PWM signal. The terminal voltage of the capacitor 3 is compared by a comparator 10 with the maximum allowable voltage, and if the terminal voltage is larger, the PWM signal is applied as the regenerative bridge control signal to the bridge 2, and if smaller, the regenerative bridge control signal is interrupted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling a bidirectional forward conversion device used in an inverter, particularly an inverter for driving a motor.

[Conventional technology]

When driving an induction motor or synchronous motor (particularly a permanent magnet rotor for a servo) with an inverter, in braking (regeneration) mode, rotational energy is regenerated and the capacitor in the DC link section is light-weighted. If this is left unattended, the capacitor voltage will continue to rise, resulting in overvoltage and eventually destruction. In order to prevent overvoltage, two methods have been used: (a) resistance discharge method and (b) power regeneration method. From this point of view, the latter b power regeneration type is the mainstream.

As the power regeneration platform and forward conversion device, a two-way single-direction conversion device is used which has a rectifying function in both directions for one-way regeneration. Bidirectional forward conversion devices often have thyristor bridges connected in antiparallel, but this requires wasted time when switching to prevent short circuits between the power and regeneration bridges, and involves frequent power and regeneration operations. The response characteristics are poor and it is unsuitable for use as a motor drive.In addition, with recent advances in PWM control technology, it has become possible to control the voltage as well as the frequency in the inverse conversion section, so the DC voltage at the DC link section can be fixed, and the powering direction Forward converters no longer require controllable functions.

In other words, as a bidirectional forward conversion device, conversion in the forward direction is performed by a simple rectifier bridge without a controllable function, and conversion in the regeneration direction is performed using a self-extinguishing switch element, making it possible to adjust the regenerative energy. The regenerative bridge is generally controlled by using the AC power supply voltage as phase information and performing sine wave PWM control or phase shift control. However, each control loop for voltage and current was complicated, and the circuit configuration was complicated.

[Problem that the invention seeks to solve]

A bidirectional forward conversion device consisting of a rectifier bridge and a regeneration bridge using self-extinguishing switching elements such as transistors, which aims to simplify the control circuit of the regeneration bridge and improve control performance. [Means to solve the problem] Use the phase voltage of the AC type W as it is as the upper limit command of the regenerative @flow, find the deflection between it and the regenerative electric motor, amplify it, compare it with the carrier waveform, and convert it into a PWM signal. Convert and further convert this into resistance b
'1 It is similar to intermittent in the same way as the % formula.

[For production]

Sine wave PWM control or a) To output the 1st order sine wave faithfully as it is.Looking at it, we put sine wave PWM control on the regeneration bridge and output the life 'la pressure as it is as @flow command. It is clear that the following circuit does not require any special processing or operation, and the circuit is extremely simple and easy to control. An example block diagram and a time chart are shown in FIG. In Figure 1, (1) is the rectifier bridge, (
2) is a regeneration bridge, and (3) is a DC link capacitor, which constitutes a bidirectional forward conversion device that allows current to flow in both directions for 5 regeneration. In the control circuit, (4) is a phase voltage detector of the AC power supply, (5) is a current detector, and (6) is a voltage detector (4) with a sine wave current command, and a current detector (5). (7) is a triangular temporary oscillator that generates a PWM carrier triangular wave, (8)
) is the first comparator that converts the sinusoidal current deviation signal into a PWM signal, (9) is the insulation detector for detecting the DC link voltage, and (10) is the maximum allowable voltage K of the DC link capacitor.
d = MAY and insulation detector output DC link voltage F
The second comparator (11) determines the magnitude relationship with the first. Sine wave PWM of second comparator (8), (10)
AND gate that superimposes the signal and the overvoltage signal, (12)
is an isolation amplifier that converts the output of the AND gate (11) into the base signal of the regenerative bridge transistor.

In other words, the current command for the line voltage is set to the maximum value that is full of the limit value, and the deviation from the detected regenerative current is taken, resulting in a sine wave current deviation signal, which is amplified via the current amplifier/regulator (6). After that, it is compared with a carrier triangular wave and converted into a sine wave PWM signal.

This sine wave PWM signal waveform is generated when the magnitude relationship between the maximum allowable voltage Ed-MAX of the DC link converter and the detected voltage Ed is Ea-MAX≦EcL.
(11) is in an open state and is used as it is as the base input of the regeneration bridge transistor. In other words, a current with a power factor of -1 flows through the line, suppressing the rise in capacitor voltage, and regenerating the rotation axis energy to the power supply side. Conversely, in the case of Ka-MAX)Bd, A
The ND gate (11) is closed, there is no output from the isolated amplifier 5 (+2), and the regeneration bridge (2) does not operate.
The regenerative current command of the AC power supply phase voltage is set to a value larger than the motor regenerative power that can be considered in advance.
Depending on the magnitude of the detected voltage E (l), the regenerative bridge can be operated or stopped on the open side j. That is, Ea
When -MAX<Kd, the regenerative current is regenerated at full maximum current, and the capacitor voltage E(l decreases to below the maximum load E(1-MAX) without passing the time shown on the left, and the regeneration bridge (2) The operation will automatically stop, and during the stop, energy will be regenerated from the room motor and the capacitor voltage will rise, but if the capacitor voltage E (l reaches the maximum voltage 3d-MAX), the regeneration bridge (2) is again a sine wave PW
When the M signal is received, a regenerative operation will be performed. The role of a limiting resistor in the so-called resistance discharge type is performed by the regenerative current command of the phase voltage, and the switch resistor is replaced with a regenerative bridge transistor.

The time chart in Figure 2 shows the operating waveforms of each part, and in order from the top, the regenerative current command a1 of the AC power supply phase voltage, the regenerative current S, the sine wave current deviation signal C of the current regulator (6) output, and the carrier triangular waveform d. , sine wave PWM signal e, allowable maximum voltage signal Ed-MAX, capacitor voltage K (1, regeneration bridge (2) base input signal f, and xa-MAX<E
When d, the sine wave PWM signal e is directly applied to the regeneration bridge (2), while when E(1-MAX)K(1), the base input of the regeneration bridge (2) is cut off.

〔Effect of the invention〕

A sine wave PWM method that faithfully outputs a sine wave of one command,
When used for regenerative current control, there is nothing wrong with using the phase voltage of the AC power supply as it is as a sine wave current command! ? This eliminates the need for separate processing and operations, greatly contributing to circuit simplification and improved control performance.

[Brief explanation of the drawing]

Claims (1)

[Claims] 1. In a bidirectional forward conversion device consisting of a rectifier bridge, an anti-parallel connected regenerative self-extinguishing element bridge, and a smoothing capacitor, the phase voltage of an AC power supply is converted into a sine wave PW.
Used as a current command for the M control system, takes the deviation from the detected regenerative current, amplifies and adjusts the current deviation, compares it with the carrier signal, converts it to a sine wave PWM signal, and sets the tolerance in advance. The maximum DC voltage value and the detected capacitor voltage are compared, and if the capacitor voltage is large, the above sine wave PWM signal is used as the regenerative bridge control signal, and if it is small, this regenerative bridge control signal is cut off. A method for controlling a bidirectional forward conversion device, characterized in that: