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Inductive load commutation method

A technology of inductive load and load current, which is applied in the electrical field, can solve problems such as long freewheeling time, low control efficiency, control device design, and production failure, and achieve the effect of continuous control and improved efficiency

Inactive Publication Date: 2010-08-04
HENAN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

It can be seen that the freewheeling time of the load is Td0=t2-t1. Since the inductance and energy storage of the inductor are not known, the fixed freewheeling time needs a certain margin, such as figure 1 As shown, the set fixed freewheeling time is Td, Td=t3-t1, Td>Td0, so the set freewheeling time Td is longer than the actual freewheeling time, so the control efficiency is very low
[0006] In production practice, when the load object of a certain type of control device may have a large difference in inductance, and the load inductance and maximum stored energy cannot be predicted, the design of the fixed length of freewheeling time may even make the control device The design and production cannot be carried out

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Embodiment 1

[0023] Figure 4 It is the main circuit of the demagnetization equipment, which adopts the H-bridge inverter circuit. The two reverse branches are composed of two switching tubes Q1, Q4 and two switching tubes Q2, Q3 respectively. The two branches are complementary and conducting; the inductance L is the load coil; the sampling resistor R is connected in series with the load coil L, the voltage on the resistor R is sampled, and divided by the resistance value of the resistor R, the sampled freewheeling current value can be obtained. By controlling the turn-on and turn-off of the four switch tubes, the output AC square wave with decreasing duty cycle, and the four switch tubes Q1, Q2, Q3, and Q4 are connected in antiparallel with four diodes D1, D2, D3, and D4 respectively. , as a freewheeling diode, providing a freewheeling path for current. After the switching tube of one branch is turned off, the load current cannot change suddenly, and the freewheeling diode of the other b...

Embodiment 2

[0026] The difference between the second embodiment and the first embodiment is that the second embodiment selects a very small positive and negative voltage value as the approximate value of the zero potential, and provides a very short delay when the detected current reaches this value. Due to the accuracy of the measurement, the zero crossing of the current may not be easy to determine. Therefore, a reference point potential is set during measurement, so that the reference point potential is very close to zero potential, and the reference point potential is used to simulate zero potential. In order to achieve this purpose, Embodiment 2 adopts a comparative current detection circuit for detecting current, and its circuit schematic diagram is as follows Figure 6 shown. The operational amplifier U1A and its peripheral circuits form an inverting amplifier, and the operational amplifiers U1B and U1C form a comparator with their peripheral circuits; four R7, R4, R6, and R8 are ...

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Abstract

The invention relates to an inductive load commutation method, and the method comprises the following steps: setting two reverse branches for supplying power to an inductive load alternately; carrying out real-time monitoring on the current of the load; and freewheeling the load whenever one branch is turned from the on-state to the off-state, and further giving a control command for turning the other branch to the on-state after monitoring that the freewheeling current is zero. The method can indirectly sense the inductance of the load and the release situation of stored energy of the load by measuring the freewheeling current in a current loop of the load, thereby being automatically applicable to the loads with different inductances according to the time which needs to switch the current direction and improving the efficiency.

Description

technical field [0001] The invention relates to the field of electricity, in particular to a method for switching the direction of current for inductive loads. Background technique [0002] The process of transferring current from one branch to another is called commutation. [0003] When commutating the inductive load, since the inductive load current cannot change suddenly, it must be stagnant for a period of time (freewheeling time), and the current output in the opposite direction can only be performed after the energy storage of the load is completely released. [0004] It is a common way to use components such as controllable switch tubes as control devices for commutation. In order to meet the requirements of load operation and protect components such as switching tubes, the usual method is to set a fixed freewheeling time for the control device through table lookup, manual or experience. However, the freewheeling time required by different loads is not the same, or...

Claims

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Application Information

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IPC IPC(8): H02M7/5387
Inventor 刘勇陈乃明高卫红张春阳赵海霞肖春宝
Owner HENAN UNIV OF SCI & TECH