CN201562001U - Direct current bus voltage sampler of intermediate-voltage transducer - Google Patents

Abstract

The utility model discloses a direct current bus voltage sampler applied to an intermediate-voltage transducer. The direct current bus voltage sampler is connected between a positive bus and a negative bus in series, the direct current bus voltage is converted into a high-frequency and low-voltage alternating current signal through a high-frequency power transformer and a high-voltage power switching tube, and the high-frequency and low-voltage alternating current signal is sent to a signal conditioning circuit for a control circuit to sample and calculate after rectification and filtering. In addition, due to the other secondary windings of the high-frequency transformer, proper voltage can be designed according to the requirement of the transducer and is used as an auxiliary power supply of the transducer. The direct current bus voltage sampler solves the problem of electrical isolation of the direct current bus voltage and a low-voltage control loop, improves the anti-interference performance of the transducer, provides the auxiliary power supply for the transducer, and has low cost and high reliability.

Description

Medium voltage frequency converter DC bus-bar voltage sampling apparatus

(1) technical field

The utility model relates to a kind of voltage sample technology, and specifically a kind of usefulness solves the voltage sample problem of dc bus in the medium voltage frequency converter.

(2) background technology

At present, in medium voltage frequency converter, the following dual mode of the many employings of the voltage sample of dc bus: mode one electric resistance partial pressure type.The serial connection high-power resistance carries out dividing potential drop between dc bus, and the low-voltage signal that will get is input to the control system Direct Sampling.Mode two Hall element formulas.Converting the dc bus high voltage to low-voltage signal with voltage hall sensor samples.Above dual mode all has shortcoming, though wherein mode one circuit structure is simple, cost is low.But main circuit and control circuit are not isolated, and system's anti-interference is poor; Though mode two main circuits and control circuit have electrical isolation, DC voltage Hall often price is very high, causes equipment cost to increase, and market is difficult to accept.

(3) summary of the invention

The purpose of this utility model provides that a kind of novel cost is low, the DC bus-bar voltage sampling apparatus that is used for medium voltage frequency converter of strong interference immunity.

The purpose of this utility model is achieved in that medium voltage frequency converter DC bus-bar voltage sampling apparatus, and it comprises high frequency switch transformer, high-voltage circuit breaker pipe, commutation diode, filter capacitor, divider resistance.The elementary serial connection high-voltage circuit breaker of high frequency switch transformer Guan Bingyu dc bus connects, the secondary serial connection commutation diode of high frequency switch transformer, and commutation diode connects filter capacitor and divider resistance.Described high frequency switch transformer secondary two-way or multichannel winding, wherein one the tunnel as the DC bus-bar voltage sampling, and other each roads can be used as the accessory power supply of transducer control circuit.

Exclusive advantage of the present utility model is:

1, the high frequency switch transformer of this device is an accessory power supply of using frequency converter, and the winding by auxiliary supply transformer carries out voltage sample.

2, this device circuit is simple in structure, and low cost of manufacture is easy to apply.

3, this device solves the isolating problem of main circuit and control circuit, improved the antijamming capability of system.

Utilize the medium voltage frequency converter DC bus-bar voltage sampling apparatus of the auxiliary supply transformer design in the frequency converter, high frequency switch transformer is wherein isolated major loop and control loop, has improved the antijamming capability of frequency converter.In addition, this sample mode has saved traditional voltage hall sensor, has reduced the cost of frequency converter, is present the most reliable most economical DC bus-bar voltage sampling apparatus through facts have proved this device.

(4) description of drawings

Figure is a medium voltage frequency converter DC bus-bar voltage sampling apparatus schematic diagram.

(5) embodiment

Below in conjunction with the accompanying drawing specific embodiment the utility model is done description in more detail:

The schematic diagram of the utility model patent as shown in the figure.Wherein T is a high frequency switch transformer, and S is a power switch pipe, D ₁, D ₂Be commutation diode, C ₁, C ₂Be filter capacitor, R ₁, R ₂Be divider resistance.The PWM that the high-voltage circuit breaker pipe provides according to control circuit (width modulation) signal carries out switch, converts DC bus-bar voltage to the high-frequency and high-voltage alternating voltage, is coupled to secondary through the transformer step-down, again through D ₁, D ₂Rectification, C ₁, C ₂Deliver to signal conditioning circuit after the filtering for the control circuit sampling.The elementary winding of high frequency switch transformer T is N ₁, secondary winding is respectively N ₂And N ₃N ₂The output voltage V of winding _CCFor the control circuit of frequency converter provides power supply.N ₃The output voltage V of winding _SThrough divider resistance R ₁, R ₂After the dividing potential drop, send into the AD sample circuit of control circuit and change, like this, the high voltage dc bus voltage in the frequency converter has just converted the digital signal of low pressure to, convenient sampling and computing.

If primary winding N ₁The number of turn be n ₁, secondary winding N ₂And N ₃The number of turn be respectively n ₂And n ₃, DC bus-bar voltage is U, then output voltage:

$V_{\mathrm{CC}}=\frac{{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="H2009201008768E00011.png"\; state="\{\{state\}\}">n</figure-callout>}}_2\&CenterDot;U}{n_1}\&times;D$

$V_s=\frac{n_3\&CenterDot;U}{n_1}\&times;D$

Wherein, D is the dutycycle of switching tube switch.

V _CCBe the accessory power supply of frequency converter, can select turn ratio on demand.V _SCan be further through divider resistance R ₁, R ₂Dividing potential drop, or nurse one's health into the required suitable value of CPU through computing circuit and sample.

Claims (2)

1. medium voltage frequency converter DC bus-bar voltage sampling apparatus that is connected between the medium voltage frequency converter positive and negative busbar, it is characterized in that: be serially connected with the elementary connection high-voltage circuit breaker of the high frequency switch transformer pipe between the positive and negative busbar, the secondary serial connection commutation diode of high frequency switch transformer, commutation diode connects filter capacitor and divider resistance.

2. according to claim 1 and 2 described medium voltage frequency converter DC bus-bar voltage sampling apparatuses, it is characterized in that: described high frequency switch transformer secondary two-way or multichannel winding, wherein one the tunnel as the DC bus-bar voltage sampling, and other each roads can be used as the accessory power supply of transducer control circuit.

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