Method for controlling an electric machine

Abstract

A method (100) for controlling an electric machine comprising two or more phases, which uses the principle of continuous conduction to reduce power loss by switching (112) at least one power stage, wherein each phase has one high-side power stage and one low-side power stage, respectively, the method comprising at least the following steps: detecting (102) required data for operating (108) the electric machine, in particular the power stages: determining (104) required currents or pulse widths of all power stages; determining (106) the power stage with the highest pulse width; operating (108) pulse width modulation, wherein the power of the electric machine is adapted; determining (110) the optimal switching point in time of the one power stage or the plurality of power stages; and switching (112) the power stages by a control device, wherein the control device generates switching commands in real time in order to control the switching (112) such that the power stage with the highest pulse width is continuously conducted, or is switched on before and switched off after the other power stages, wherein the power stages are only switched (112) when the other power stages are switched off, wherein the plurality of other power stages are switched on and off in a combined manner in succession, wherein it is ensured that for the same phase the high-side power stage and the low-side power stage are not switched on at the same time at any time.

Description

Technical Field

[0001] This invention relates to a method for controlling a motor comprising two or more phases, the method employing a continuous conduction principle to reduce power losses by switching at least one power stage. Furthermore, the invention also relates to the use of said method for controlling a three-phase motor. Background Technology

[0002] DE 10 2019 208 524 A1 relates to a method for controlling the operation of an inverter for a motor, wherein pulse width modulation values ​​for at least two phases are set in at least two cycles by: performing a first setting of the pulse width modulation values ​​for each phase in a current measurement cycle, performing a current measurement of at least one current of the motor in the current measurement cycle, and setting the pulse width modulation values ​​for the phases in at least one additional cycle based on the pulse width modulation values ​​set in the current measurement cycle.

[0003] WO 2019 0158 94 A1 relates to an electric motor, i.e., a motor and / or a generator. The motor has a stator and a rotor. The rotor is, in particular, permanent magnet or current-carrying. The motor is divided into at least two sub-motors. Each sub-motor has the same number of phases. According to the invention, the motor has two power final stages for each sub-motor. The motor also has at least one control unit connected to the power final stages. To control the power final stages, the control unit is configured to generate pulse width modulation (PWM) signals. The control unit is also configured to generate PWM signals for the sub-motors such that the falling or rising edge of the PWM pulse representing the switching time point of one sub-motor is time-staggered from the midpoint of the PWM pulse of the other sub-motor. Summary of the Invention

[0004] According to the present invention, a method for controlling a motor having two or more phases is proposed, which uses a continuous conduction principle to reduce power loss by switching at least one power stage. Here, each phase has a high-side power stage and a low-side power stage. The method includes at least the following steps: a. Obtain the necessary data for controlling the motor. b. Determine the necessary pulse widths for all power levels. c. Determine the power stage with the highest pulse width, and d. Manipulating pulse width modulation i. Determine the optimal switching time for the one or more power stages, and ii. Switching the power stages via a control device, wherein the control device generates switching commands in real time to control the switching such that the power stage with the highest pulse width is continuously turned on, wherein continuous turn-on corresponds to setting the pulse width to 100%, or being turned on before other power stages and turned off after other power stages, wherein the switching of this power stage only occurs when other power stages are turned off. iii. Several other power stages are sequentially turned on and off in combination, ensuring that for the same phase, the high-side power stage and the low-side power stage are never turned on simultaneously at any time.

[0005] An electric motor, also known as a multiphase motor or three-phase AC motor, is an electromechanical device that uses multiple independent sinusoidal alternating voltages or currents to generate mechanical work or convert electrical energy, and operates in two or more phases. This is understood as an electrical state represented by sinusoidal currents or voltages in the system. In a multiphase motor, the phases are offset from each other by a certain angle, for example, 120 degrees in a three-phase AC motor. This phase offset produces a uniform and continuous torque, resulting in efficient rotary motion.

[0006] High-side and low-side power stages are understood as components in a power electronic circuit unit used to control the current flow through a motor. In single-phase and multi-phase electrical systems, such as three-phase applications, there is a corresponding power stage for each phase. The high-side power stage represents the switch located on the positive voltage side. It controls the tap change between the power supply voltage and the motor load. Conversely, the low-side power stage represents the switch located on the negative voltage side. It controls the connection between the load and the reference potential. These power stages, by selectively activating and deactivating them, control the current flow and direction (i.e., rotation direction) and current intensity to achieve desired efficiency.

[0007] To adapt the power output to the motor, pulse width modulation (PWM) is used. In this method, the pulse width of the PWM signal is changed, thereby adjusting the average power. PWM control is performed by a control device, such as a microcontroller. The control device analyzes and processes the analyzed data to pre-determine the optimal switching time for the power stages. Taking into account the required current intensity in the power stages, the control device can adjust the PWM to achieve efficient power regulation on the motor. For example, when manipulating PWM, the optimal switching time is determined using the current intensity detected by sensors and analyzed by the microcontroller. Based on the analysis of the current intensity and operational requirements, the optimal switching time for all power stages is determined. The switching time is determined to maximize both efficiency and optimize the motor load. This is achieved either by continuously turning on the power stage with the highest current intensity, i.e., keeping the power stage with the highest current intensity continuously active until it is the turn of another power stage with a higher current intensity, and by sequentially turning on and off multiple other power stages in combination, ensuring that the high-side power stage and the low-side power stage for the same phase are never simultaneously turned on at any given time. Subsequently, the control device adapts to pulse width modulation to control the motor's power demand. After determining the optimal switching time, the power stage is switched accordingly by the control device.

[0008] As an alternative to keeping the power stage with the highest current intensity continuously on, this power stage can also be switched at times other than the switching process of other power stages, so that the other power stages are off during the switching of this power stage.

[0009] In an advantageous extension of the method proposed according to the invention, the power stages in the inverter are switched such that they are activated or deactivated according to control.

[0010] In another advantageous extension of the method proposed according to the invention, the control includes adaptive adaptation of pulse width modulation based on the current operating conditions of the motor.

[0011] In another advantageous extension of the method proposed according to the invention, current intensity, voltage, torque and speed are detected on each phase of the motor, wherein the detection of parameters can be performed individually and in combination.

[0012] In another advantageous extension of the method proposed according to the invention, the current intensity of the power stage is detected in real time by a sensor.

[0013] In another advantageous extension of the method proposed according to the invention, the current intensity of the power stage is detected by a sensor selected from the group consisting of Hall sensors, current transformer sensors, or shunt resistors.

[0014] Furthermore, the present invention also relates to the use of the method for controlling a three-phase motor.

[0015] Advantages of the present invention The solution according to the invention advantageously provides a method for controlling a motor having two or more phases, which uses a continuous conduction principle to reduce power losses by switching at least one power stage. By optimizing the conduction principle—that is, continuously conducting the power stage with the highest current intensity among the group of power stages for each phase of the motor—the operating efficiency of the motor is improved. Furthermore, the continuous conduction principle of the power stages achieves energy consumption reduction, thereby realizing cost savings.

[0016] Due to the continuous conduction principle, the solution according to the invention can improve the lifespan of the power stage by operating with less voltage stress and thus with less wear and failure tendency.

[0017] In electric motor-driven vehicles or other equipment, greater travel lengths are achieved through efficient utilization and reduced power losses. Alternatively, less energy is required to achieve the same travel length, thus reducing the costs of energy supply and storage.

[0018] Furthermore, by maintaining the power stage continuously on, more efficient operation is achieved through controlling and reducing power losses, resulting in less heat generation within the power stage compared to existing technologies. This reduces the need for complex cooling systems, saving costs and advantageously reducing system complexity.

[0019] Furthermore, the solution according to the invention is suitable for integration into existing systems, requiring only reprogramming of the control device, including a microcontroller or PLC. The method corresponding to the solution according to the invention can also be advantageously applied to a variety of motors having phases. Attached Figure Description

[0020] Embodiments of the present invention will be further described based on the accompanying drawings and the following description.

[0021] The attached diagram shows: Figure 1 A schematic diagram of a method for controlling a motor. Figure 2 A schematic diagram of the phases and power stages of a three-phase motor. Figure 3.1 A graphical representation of the curves of the three phases. Figure 3.2 A graphical representation of the continuous conduction principle. Detailed Implementation

[0022] In the following description of embodiments of the invention, the same or similar elements are denoted by the same reference numerals, wherein repeated descriptions of these elements are omitted in certain cases. The accompanying drawings are merely schematic illustrations of the subject matter of the invention.

[0023] Figure 1 An exemplary method 100 according to the present invention for controlling a motor 202 having two or more phases 204, 206, 208 is illustrated schematically as a block diagram. The method uses a continuous conduction principle 302 to reduce power loss by switching 112 at least one power stage 204.1, 204.2, 206.1, 206.2, 208.1, 208.2. Here, in the first step, detection 102 of data required to manipulate 108 the power stages 204.1, 204.2, 206.1, 206.2, 208.1, 208.2 is performed. For example, the current intensity of the power stages 204.1, 204.2, 206.1, 206.2, 208.1, 208.2 can be detected and continuously monitored by a Hall sensor, a current transformer sensor, or a shunt resistor. The sensor continuously monitors current flow and current intensity and detects data in real time. This data is then, for example, forwarded to control device 210, whereby it is adapted accordingly to the changing current intensity.

[0024] In the second step, the required current intensity is determined 104, more precisely, individually for each power stage 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2. Here, each power stage 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 is analyzed separately. The required current intensity or pulse width is determined for each power stage 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2.

[0025] In the third step of the method 100 according to the invention, the control device 210 determines 106 and compares the necessary pulse widths of the power levels 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 with each other, and identifies the power levels 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 with the highest necessary pulse width.

[0026] In the fourth step of the method 100 according to the invention, pulse width modulation 216 is manipulated 108 to adapt the power of the motor 202. The manipulation 108 of the pulse width modulation 216 undergoes at least sub-method steps i. and ii. In sub-method step i., the optimal switching time points of one or more power levels 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 are first determined 110 based on the analyzed current intensity. In another sub-step ii. of the fourth process step d., the switching 112 of the power levels 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 is performed by control device 210. The control device 210 operates in real time and generates switching commands to control the circuit unit 200 such that the power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 with the highest current intensity are permanently turned on, and multiple other power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 are sequentially activated and deactivated in combination 306.

[0027] As an alternative to the continuous conduction 302 of power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 with the highest current intensity, this power stage can also be switched at a time outside the switching process of other power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2, so that during the switching 112 of this power stage 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2, the other power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 are off. Here, by means of the method 100 according to the invention, it is always ensured that the high-side power stage 212 and the low-side power stage 214 for the same phase 204, 206, and 208 are never simultaneously turned on at any time.

[0028] Figure 2 A schematic diagram of a circuit unit 200 for a three-phase motor 202 is shown, which includes a control device 210 with pulse width modulation 216. The circuit unit 200 has a total of six power stages 204.1, 206.1, 208.1, 204.2, 206.2, and 208.2, which can be implemented by transistors or similar semiconductor switches. The power stages 204.1, 206.1, 208.1, 204.2, 206.2, and 208.2 are respectively divided into a high-side power stage 212 and a low-side power stage 214 to achieve optimal power delivery. Figure 2As can be seen, the first, second, and third power stages 204.1, 206.1, and 208.1 correspond to the first, second, and third high-side power stages 212.1, 212.2, and 212.3. The fourth, fifth, and sixth power stages 204.2, 206.2, and 208.2 correspond to the first, second, and third low-side power stages 214.1, 214.2, and 214.3. Each power stage 204.1, 206.1, 208.1, 204.2, 206.2, and 208.2 is connected to a corresponding phase 204, 206, or 208, which controls the energy supply to the motor 202.

[0029] By dividing the power supply into a high-side power stage 212 and a low-side power stage 214, fine control of the energy flow through phases 204, 206, and 208 of the motor 202 is provided. Here, the high-side power stage 212 switches the positive voltage side and provides efficient control of the current flow through each phase 204, 206, and 208. This allows for direct voltage setting, which is crucial for precise speed regulation. Conversely, the low-side power stage 214 switches the negative side of the voltage source. Together with the high-side power stage 212, they are used to regulate the current flow through phases 204, 206, and 208 of the motor 202. This division enables more precise control of the phase current, thereby improving both efficiency and system stability.

[0030] Figure 2The circuit unit 200 shown has a control device 210 with pulse width modulation 216, which ensures precise regulation of the power stages 204.1, 206.1, 208.1, 204.2, 206.2, and 208.2. The control device 210 modulates the pulse width of the pulse width modulated signal 216 supplied to the power stages 204.1, 206.1, 208.1, 204.2, 206.2, and 208.2 to control the power supply to the motor 202. Here, the pulse width modulation 216 controls the switching 112 of the power stages 204.1, 206.1, 208.1, 204.2, 206.2, and 208.2 such that the power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 with the highest current intensity are permanently turned on, and multiple other power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 are sequentially activated and deactivated in combination 306. This, for example, enables precise adjustment of the speed of the motor 202 to optimize operation according to the requirements of the corresponding application. For example, the circuit unit 200 may include multiple sensors to monitor important operating parameters such as speed, current, voltage, and temperature. This feedback information is used by the control device 210 to adapt the pulse width modulation 216 accordingly and ensure optimal power output, while simultaneously ensuring optimal efficiency and reliability.

[0031] Furthermore, the control device 210 monitors and regulates the operation 108 of phases 204, 206, and 208, ensuring that the current of phases 204, 206, and 208 operates normally and in accordance with the grid voltage without failure. This ensures the stable and efficient operation of the motor 202. The circuit unit 200 can also be equipped with various protection devices, particularly overcurrent protection, overvoltage protection, and temperature monitoring, to protect the motor 202 from damage and ensure safety.

[0032] Figure 3.1 The time curves for three phases 204, 206, and 208 are shown. The horizontal axis represents time 308, while the vertical axis represents the voltage 310 or, for example, the current 312 in each phase 204, 206, and 208. For illustration of the time curves, each phase 204, 206, and 208 is represented by its own line. From Figure 3.1 As can be seen from the diagram, phases 204, 206, and 208 are synchronized with each other and have sinusoidal waveforms characteristic of alternating current.

[0033] Figure 3.2A schematic diagram is shown for six power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 for each of the three phases 204, 206, and 208. The phases 204, 206, and 208 are identified by their respective power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2. Here, horizontal bars represent the power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2, while vertical bars represent the chronological order in which these power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 are activated or deactivated. Figure 3.2 This shows how the power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 in each phase 204, 206, and 208 are continuously and sequentially activated by 304 to control current flow and ensure the desired power output to the motor 202. Figure 3.2 It can also be seen that the horizontal bars of each power stage 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 have two regions. The first region indicates that the power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 are sequentially turned on (304), and the second region indicates continuous conduction (302). Here, the power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 with the highest current intensity are activated by continuous conduction. Furthermore, from... Figure 3.2 As can be seen, when combined with the continuously conducting 302 in combination with 306, one power stage 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 will activate and deactivate two other power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 respectively, but this ensures that the high-side power stage 212 and the low-side power stage 214 used for the same phase 204, 206, and 208 will not be turned on simultaneously at any time.

[0034] As an alternative to the continuous conduction 302 of power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 with the highest pulse width, this power stage can also be switched at a time outside the switching process of other power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2, such that during the switching 112 of this power stage 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2, the other power stages 204.1, 204.2, 206.1, 206.2, 208.1, and 208.2 are off. The method steps are not described in... Figure 3.2 As shown in the image.

[0035] This invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, numerous modifications that are within the scope of the claims are possible and are well understood by those skilled in the art.

Claims

1. A method (100) for controlling a motor (202) comprising two or more phases (204, 206, 208), the method employing a continuous conduction principle (302) to reduce power losses by switching (112) at least one power stage (204.1, 204.2, 206.1, 206.2, 208.1, 208.2), wherein each phase (204, 206, 208) has a high-side power stage (212) and a low-side power stage (214), the method comprising at least the following steps: a. Detect (102) the data required for controlling (108) the motor (202), particularly the power stages (204.1, 204.2, 206.1, 206.2, 208.1, 208.2), b. Determine the required current or pulse width for all power stages (204.1, 204.2, 206.1, 206.2, 208.1, 208.2) of (104). c. Identify the power stages (204.1, 204.2, 206.1, 206.2, 208.1, 208.2) with the highest pulse width (106). d. Manipulating (108) pulse width modulation (216), wherein the power of the motor (202) is adapted, i. Determine (110) the optimal switching time for one or more power stages (204.1, 204.2, 206.1, 206.2, 208.1, 208.2), and ii. The power stages (204.1, 204.2, 206.1, 206.2, 208.1, 208.2) are switched (112) by a control device (210), wherein the control device (210) generates a switching command in real time to control the switching (112) such that the power stage (204.1, 204.2, 206.1, 206.2, 208.1, 208.2) with the highest pulse width is continuously turned on (302), wherein the continuous turn on (302) corresponds to setting the pulse width to 100%, or in other power stages... The switching (112) of the power stages (204.1, 204.2, 206.1, 206.2, 208.1, 208.2) is performed before the other power stages (204.1, 204.2, 206.1, 206.2, 208.1, 208.2), wherein the switching (112) of the power stages (204.1, 204.2, 206.1, 206.2, 208.1, 208.2) only occurs when the other power stages (204.1, 204.2, 206.1, 206.2, 208.1, 208.2) are turned off. iii. Multiple other power stages are sequentially turned on and off in combination, ensuring that the high-side power stage (212) and the low-side power stage (214) are never turned on simultaneously for the same phase at any time.

2. The method (100) of claim 1, wherein the determination (106) comprises comparing the detected current intensities of the power levels (204.1, 204.2, 206.1, 206.2, 208.1, 208.2) with each other.

3. The method (100) according to claim 1 or 2, wherein the power stages (204.1, 204.2, 206.1, 206.2, 208.1, 208.2) are switched (112) in the inverter such that the power stages are activated or deactivated according to the control (108).

4. The method (100) according to any one of the preceding claims, wherein the manipulation (108) includes adaptive adaptation of the pulse width modulation (216) based on the current operating conditions of the motor (202).

5. The method (100) according to any one of the preceding claims, wherein current intensity, voltage (310), torque and speed are detected (102) on each phase (204, 206, 208) of the motor (202), wherein the detection (102) of the parameters can be performed individually and in combination.

6. The method (100) according to any one of the preceding claims, wherein the detection (102) of the current intensity of the power stages (204.1, 204.2, 206.1, 206.2, 208.1, 208.2) is performed in real time by a sensor.

7. The method (100) according to any one of the preceding claims, wherein the detection (102) of the current intensity of the power stage (204.1, 204.2, 206.1, 206.2, 208.1, 208.2) is performed by a sensor selected from the group consisting of a Hall sensor, a current transformer sensor or a shunt resistor.

8. Use of the method (100) according to any one of claims 1 to 7 for controlling a motor (202) having three phases (204, 206, 208).

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