The bypass circuit of high voltage variable frequency speed regulator
Technical field
The present invention relates to a kind of circuit, refer to a kind of bypass circuit of power model series connection high voltage variable frequency speed regulator especially.
Background technology
Along with the development of power electronic technology, the application of high voltage variable frequency speed regulator is day by day extensive.Particularly, the high-voltage variable-frequency and variable-speed system that is made of power model series connection is as the frequency converter that is fit to China's actual conditions, excellent performance, more and more be subjected to numerous frequency converter production firm, scientific research institutions, engineers and technicians, user's favor, shown the prospect that it is in the ascendant.It is 95119585.9 and 97100477.3 patent application that the detailed description of this frequency converter sees also Chinese application number.
This high voltage converter in use the situation that certain or certain several power models break down can occur once in a while, at this moment just needs a bypass circuit urgently.When single or several power models break down in the high voltage variable frequency speed regulator that the power model series connection constitutes, can its bypass be gone out system by bypass circuit, and continue to power, thereby not influence the operation of system to motor by remaining power model.
At present, the bypass circuit that uses in the domestic high voltage converter mainly contains two kinds.A kind of is the bypass circuit that is made of relay, and its shortcoming is: because the mechanical contact loose contact sometimes of relay or can not precision maneuver has influenced the reliability of system.
Now the bypass circuit of the another kind of form that generally adopts as shown in Figure 1, it is made of single-phase diode rectifier bridge 2 that is arranged on inverter bridge 1 next door and controllable silicon 3.When certain power model broke down, inverter bridge 1 was turn-offed by system, triggered controllable silicon 3, and electric current is flow through by the path that diode rectifier bridge 2 and controllable silicon 3 form.But there is certain problem in actual applications in this bypass circuit, and promptly bypass circuit can not really play the effect of bypass fault power module.Because it has proposed higher requirement to diode in the bypass circuit and controllable silicon, as everyone knows, the switching time of IGBT is very short, generally about 300 nanoseconds, use the IGBT of 1700V now, DC bus-bar voltage can reach about 1000V, so the dv/dt that produces during the IGBT switch will be in the magnitude of 3000V/us, and the dv/dt that controllable silicon can bear is generally below 1000us.So, circuit shown in Figure 1, when just powering on, the voltage at controllable silicon two ends is zero, when the moment of power model (as IGBT) beginning normally, controllable silicon will tolerate the dv/dt above its tolerance.When silicon controlled junction capacitance, circuit physical impedance and stray reactance hour, will cause that silicon controlled misleads, thereby cause the inverter bridge output short-circuit, cause the power model fault.
Can increase the measure of restriction dv/dt at the U of Fig. 1, V place, such as powering up sensor, resistance etc., still, when the power model bypass moved, they will flow through big electric current, made like this that its power consumption is big, volume is big, cost is high.
Summary of the invention
In view of the foregoing, the purpose of this invention is to provide a kind of reliable operation, low in energy consumption, high voltage variable frequency speed regulator bypass circuit that cost is little.
For achieving the above object, the present invention takes following design: a kind of bypass circuit of high voltage variable frequency speed regulator, it comprises diode rectifier bridge and the controllable silicon that is connected in parallel on each power model side of high voltage variable frequency speed regulator outlet side, it is characterized in that: it also comprises a pre-charge circuit, described pre-charge circuit be connected on frequency changer direct current bus outlet side, each power model and and its diode connected in parallel rectifier bridge, controllable silicon between.
Described pre-charge circuit is made of charging resistor and charging capacitor; Described charging resistor is serially connected between the direct current positive bus or the controllable silicon in negative busbar and the bypass circuit of frequency converter output; Controllable silicon in the bypass circuit other also charging resistor and the charging capacitor of a serial connection in parallel.Described charging resistor also can be serially connected between the positive and negative bus of direct current and the controllable silicon in the bypass circuit of frequency converter output.
Described pre-charge circuit is made of charging inductance, capacitance, charging resistor and charging capacitor; Described charging inductance and capacitance are serially connected between the direct current positive bus or the controllable silicon in negative busbar and the bypass circuit of frequency converter output; Controllable silicon in the bypass circuit other also described charging resistor and the charging capacitor of a serial connection in parallel.Described charging inductance and capacitance also can be serially connected between the positive and negative bus of direct current and the controllable silicon in the bypass circuit of frequency converter output.
Because the present invention adopts above technical scheme, promptly before the work of high voltage frequency converter power module, be designed to whole shutoffs the power model (as IGBT), before power model (as IGBT) beginning switch motion, at first the voltage with controllable silicon two ends in the bypass circuit is charged to d-c bus voltage value in advance.Like this, when beginning to move, diode in the bypass circuit and controllable silicon will no longer bear the dv/dt value above its tolerance at power model (as IGBT), thereby guarantee the security reliability of system.
Description of drawings
The invention will be further described below in conjunction with accompanying drawing.
Fig. 1 is a bypass circuit circuit diagram in the prior art
Fig. 2 is a bypass circuit circuit diagram of the present invention
Fig. 3 is the bypass circuit circuit diagram of the another kind of form of the present invention
Fig. 4 is the bypass circuit circuit diagram of another form of the present invention
Fig. 5 is the bypass circuit circuit diagram of another form of the present invention
Embodiment
The present invention is for fear of the moment that begins normally at power model (as IGBT, GTR etc.), and controllable silicon causes that because of the dv/dt of tolerance above its tolerance silicon controlled misleads, and causes the inverter bridge output short-circuit, causes the power model fault.At the other bypass circuit in parallel of each power model of high voltage converter inverter bridge side.
As shown in Figure 2, described bypass circuit is made of diode rectifier bridge 2, controllable silicon 3 and pre-charge circuit 4.Cross pre-charge circuit 4 parallel diode rectifier bridges 2 and controllable silicon 3 in frequency changer direct current bus outlet side, each power model bypass.Pre-charge circuit 4 is made of charging resistor R1, R2, R3 and charging capacitor C1; Between the positive and negative bus of direct current that resistance R 1, R2 are serially connected in frequency converter output and the controllable silicon 3, resistance R 3 be connected in parallel on controllable silicon 3 after capacitor C 1 is connected by.By pre-charge circuit 4, be resistance R 1, R2, R3, C1, when system has just been powered on, the voltage at controllable silicon two ends is precharged to d-c bus voltage value immediately, like this, when power model (as IGBT) switch, they will no longer bear the dv/dt value above its tolerance, and system reliability strengthens greatly.When power model breaks down, can be bypassed by bypass circuit veritably, and continue to power to motor by remaining power model.When power model breaks down by bypass, will there be electric current to flow through R1, R2, because R1, R2 resistance are very big, this power consumption can be ignored.Wherein, R1 or R2 also can omit, and only place a charging resistor R1 or R2 at frequency converter positive bus-bar or negative busbar place, do not influence goal of the invention of the present invention on the principle.
Fig. 3 is the bypass circuit circuit diagram of the another kind of form of the present invention.The difference of the bypass circuit of this form and bypass circuit shown in Figure 2 is: pre-charge circuit 4 is made of inductance L 1, L2, capacitance C2, C3, resistance R 3 and capacitor C 1.Inductance L 1, L2, capacitor C 2, C3 are serially connected in the frequency converter direct current and export in positive and negative bus and the bypass circuit between the controllable silicon 3, and resistance R 3 is with to be connected in parallel on controllable silicon 3 after capacitor C 1 is connected other.By pre-charge circuit 4, be inductance L 1, L2, capacitor C 2, C3, resistance R 3, capacitor C 1, when system has just been powered on, the voltage at controllable silicon two ends is precharged to d-c bus voltage value immediately, like this, when power model (as IGBT) switch, they will no longer bear the dv/dt value above its tolerance, and system reliability strengthens greatly.Break down and to be bypassed by bypass circuit veritably at power model, and continue to power to motor by remaining power model.Wherein, L1, C2 or L2, C3 also can omit, and only place a system charging inductance L1, capacitor C 2 or L2, capacitor C 3 at frequency converter positive bus-bar or negative busbar place, do not influence goal of the invention of the present invention on the principle.
When controllable silicon in the bypass circuit is just powered in system, the voltage at controllable silicon two ends promptly is precharged to d-c bus voltage value, thereby avoid being misleaded because of the dv/dt value of bearing above its tolerance at power model switch moment controllable silicon, cause the short circuit of inverter bridge outlet side, cause the power model fault, increased pre-charge circuit in the present invention's bypass circuit in the prior art, this pre-charge circuit can also derive other forms, as Fig. 4, shown in Figure 5, equal and the Fig. 2 of its operation principle, bypass circuit operation principle shown in Figure 3 is identical, auspicious no longer one by one here stating.
The above is specific embodiments of the invention only, does not limit protection scope of the present invention with this.Any equivalent transformation that those skilled in the art do based on technical solution of the present invention all belongs within the protection range of the present invention.