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power converter

A technology of power converter and voltage conversion, applied in the direction of electronic commutator, electronic commutation motor control, electrical components, etc., can solve the problems of high price and no sensor of position sensor, and achieve the effect of reducing detection error and no impact start

Active Publication Date: 2020-03-24
HITACHI IND EQUIP SYST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The frequency and phase can be detected by using a position sensor, but the position sensor is expensive, so the method of detecting the frequency and phase without a sensor by detecting the induced voltage (residual voltage) generated during the free movement of the motor is used

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0037] Embodiment 1 adopts a circuit structure that generates a virtual neutral point. All the three-phase lower arms are turned on, and the negative potential is output to all output phases of the power converter, and a three-phase balance state is established. Thus, a method of detecting an offset voltage based on the fact that the reference voltage input to the control unit is equal to the virtual neutral point will be described.

[0038] image 3 shows a configuration example of a power converter when phase voltage detection is performed, Figure 4~6 A schematic diagram showing one phase of the phase voltage detected by the control unit 34, Figure 7 It is a figure which shows the example of the flowchart of the process of a control part.

[0039] The induced voltage of the motor is in a balanced state. Therefore, for example, when the induced voltages of each phase of a three-phase motor are Vu, Vv, and Vw, and the virtual neutral point is Vneutral, their relationship ...

Embodiment 2

[0069] Embodiment 2 adopts a circuit structure for generating a virtual neutral point. Connect the motor to the output terminal, and input the voltage in the three-phase balanced state to the power converter. Thus, a method of detecting an offset voltage based on the fact that the reference voltage input to the control unit is equal to the virtual neutral point will be described. In addition to the motor, a voltage generating source capable of inputting a voltage in a three-phase balanced state, such as a generator and a power supply, may be connected.

[0070] Figure 8 An example of the structure of the power converter when the voltage is input from the output terminal is shown, Figure 9 It is a figure which shows the flowchart of the process of a control part.

[0071] use Figure 9 , the flow of the process of detecting the offset voltage by the control unit 84 will be described. When the detection is started (S91), with all the phases 205-210 as switching elements o...

Embodiment 3

[0091] Embodiment 3 adopts a circuit structure for generating a virtual neutral point. The method of detecting the offset voltage using the detection value of the DC voltage when the reference voltage input to the control unit is not equal to the virtual neutral point by turning on all three-phase upper arms will be described.

[0092] As one of the methods, in Figure 10 A circuit configuration in which the DC voltage detection unit 105 is added to the circuit configuration described in the first embodiment is shown in . The DC voltage detection unit 105 detects the voltage of the positive electrode potential based on the negative electrode potential of the DC conversion unit 202 .

[0093] use Figure 13 , the flow of the process of detecting the offset voltage by the control unit 104 will be described. When the detection is started (S131), the three-phase upper arms 205 to 207 which are switching elements of the AC conversion unit 203 are turned on (S132). At this time,...

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PUM

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Abstract

When the motor is in a free-running state, it is necessary to detect the frequency and phase of the motor in order to restart smoothly without shock. By detecting the induced voltage, the frequency and phase can be detected without sensors, but when the induced voltage is converted into an analog value, an offset voltage is generated with respect to the reference voltage, and a detection error occurs. Therefore, the power converter includes: a voltage detector that detects the voltage at its output terminal; a detection voltage generation unit that converts the voltage detected by the voltage detector into an arbitrary voltage; and using the voltage converted by the detection voltage generation unit to detect The voltage detector detects the induced voltage generated by the motor by the control unit detecting the offset voltage generated by the voltage generating unit, and the control unit corrects the detected value of the induced voltage using the offset voltage.

Description

technical field [0001] The present invention relates to power converters. Background technique [0002] Currently, in order to realize a low-carbon society, power converters such as inverters are used for driving electric motors. Among them, a state where the motor is rotated by an external force such as a fan or a pump, and a state where the motor is rotated by inertia without an output from the inverter are referred to as a free-run state. When the motor is in a state of free movement, the inverter is also required to start smoothly without impact. [0003] In order to perform a smooth restart, it is necessary to detect the frequency (speed) and phase of the motor. The frequency and phase can be detected by using a position sensor, but the position sensor is expensive, so a method of detecting the frequency and phase sensorlessly by detecting an induced voltage (residual voltage) generated during free motion of the motor is used. [0004] prior art literature [0005] ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02P6/18H02P27/06
CPCH02M7/48H02P6/187H02P27/06
Inventor 八木原茂俊田边启辅小沼雄作杉本卓也
Owner HITACHI IND EQUIP SYST CO LTD
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