KR20180007567A - Method and apparatus for measuring average current of 3 phase motor based on current measurement of pwm on-duty period - Google Patents

Abstract

According to an embodiment of the present invention, a voltage measurement circuit measuring a voltage on both ends of a dividing resistor to measure a current flowing on a three-phase motor includes: an edge extracting unit which detects the rising and falling edges of pulse width modulation (PWM) signals for controlling the three-phase motor to output rising and falling edge detection signals; a sample and holding circuit which samples the voltage on both ends of the dividing resistor when detecting edges based on the rising and falling edge detection signals; and a low frequency band pass filter which receives signals output from the sample and holding circuit to pass the low frequency band of output signals of the sample and holding circuit. According to the present invention, the voltage measurement circuit can significantly reduce the resource loads on a microcontroller unit (MCU) compared to a conventional three-phase motor control system executing an analog-digital conversion (ADC) trigger module as a separate software module and utilize the save MCU resources for a control operation for vehicle safety, thereby significantly contributing to vehicle safety.

Description

TECHNICAL FIELD [0001] The present invention relates to a voltage measurement circuit for measuring current of a three-phase motor, a three-phase motor control system, and a current measurement method of a three-phase motor.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current measuring method for a three-phase motor, and more particularly, to a method and an apparatus for measuring an average current of a three-phase motor through current measurement of a PWM (Pulse Width Modulation) on- will be.

As the electronics of automobiles progress, the number of motors that make up parts of automobiles and their roles are increasing day by day. In recent years, more and more electric motors have been installed in luxury cars. In particular, as the spread of hybrid electric vehicles and electric vehicles is beginning to expand, the status of motors as automobile parts continues to increase. Therefore, motor control technology has become a core technology of automobiles.

A PWM (Pulse Width Modulation) method is widely used as a current control method of a brushless direct current (BLDC) motor, which is widely used as a power source in hybrid cars and electric vehicles. The PWM method is an efficient current control method that controls the average value of the current flowing through the motor coil through high-speed switching while adjusting the pulse width.

For motor control through the PWM method, it is necessary to obtain an average current value flowing through the motor in order to know the rotation speed of the motor and the like. Conventionally, a method of measuring by software through a microcontroller unit (MCU) has been widely adopted. Hereinafter, a method of measuring an average current value using conventional software through an MCU will be described with reference to FIGS. 12 to 14. FIG.

12, a conventional three-phase motor control system 2000 includes an MCU 2010, a predriver 2020, a high voltage side switching unit 2030, a low voltage side switching unit 2040, a motor 2050, A shunt resistor 2060, and a buffer 2070, as shown in FIG.

The MCU 2010 transmits the PWM signal to the pre-driver 2020 via the PWM transmission line 2015 for driving the motor. As shown in FIG. 20, three signal lines are used to transmit three PWM control signals for a three-phase motor.

The pre-driver 2020 controls the high-voltage-side switching unit 2030 and the low-voltage-side switching unit 2040 based on the control signal received from the MCU 2010 to supply current to the motor. More specifically, the pre-driver 2020 includes a high-voltage-side gate control unit 2021 and a low-voltage-side gate control unit 2022, and includes a high-voltage-side switching unit 2030 and a low- A high voltage and / or a low voltage are applied to the gates of the switches 2031 and 2041 to turn on and / or off the switches 2031 and 2041.

On the other hand, a current flowing through the motor 2050, the high-voltage side switch 2031 and the low-voltage side switch 2041 is passed through the dividing resistor 2060, and the buffer 2070 is connected to the dividing resistor 2060, The voltage across both ends is transmitted to the MCU 2010 again.

The MCU 2010 receives the voltage value from the buffer 2070 through the analog input terminal 2013 and converts the received voltage to a value related to the average current through an ADC (Analog to Digital Converter) 2012, And controls the pre-driver 2020 and the motor 2050 again using the average current value.

13 (a) and 13 (b), when both the high-voltage side switch 2031 and the low-voltage side switch 2041 are in the ON state, current flows to the dividing resistor 2060 However, when only the low-voltage switch 2041 is in the on-state, no current flows through the voltage-dividing resistor 2060, so that the voltage can not be measured.

Will be described in more detail with reference to the timing chart of Fig.

When the PWM control signal 2210 outputted from the MCU 2010 is in the ON state, a voltage equal to the signal 2220 is actually applied to both ends of the classification resistor 2060. More specifically, the current flowing in the three-phase motor 2050 continuously increases while the PWM signal is applied, and the current flowing in the three-phase motor 2050 decreases while the PWM signal is not applied.

The ADC 2012 receives the voltage across the voltage divider resistor 2060 from the analog input terminal 2013 and reads the voltage value at the time when the signal is applied from the ADC Triggering Module (ATM). According to the prior art, the ADC trigger module is a software module that calculates the software intermediate point of the on-state of the PWM signal and allows the ADC 2012 to read the voltage value transmitted from the buffer 2070 as a digital value at that point do. The control signal transmitted from the ADC trigger module 2011 to the ADC 2012 is the same as the signal 2230. Considering that the voltage across the voltage divider resistor 2060 linearly increases in a section in which the PWM signal is on, the ADC 2012 is activated at the midpoint of the on- Is implemented to read the voltage value.

Therefore, the voltage value read by ADC 2012 actually reads the voltage value in the form of signal 2240, for example.

However, in the case of the conventional configuration, the MCU 2010 consumes a considerable amount of resources. In the case of the MCU 2010 used for automobile control and the like, it is often necessary to monitor the data in real time or to process the data in a stable manner.

It is an object of the present invention to substantially obviate various problems caused by the limitations and disadvantages of the prior art, and it is an object of the present invention to provide an ADC A three-phase motor control system, and a motor current measurement method, which are equipped with a voltage measurement circuit without a separate software module for triggering the three-phase motor control system.

In order to achieve the above object, in order to measure a current flowing in a three-phase motor according to an embodiment of the present invention, a voltage measuring circuit for measuring a voltage across both ends of the voltage dividing resistor comprises a PWM (Pulse Width An edge extraction unit for detecting a rising edge and a falling edge of a modulation signal and outputting a rising edge detection signal and a falling edge detection signal; A sample and hold circuit for sampling a voltage across the split voltage at edge detection based on the rising edge detection signal and the falling edge detection signal; And a low pass filter that receives the signal output from the sample and hold circuit and passes the low frequency band of the output signal of the sample and holding circuit.

Also, the sample and holding circuit may include a rising edge voltage measuring unit and a falling edge voltage measuring unit.

Further, the rising edge voltage measuring unit and the falling edge voltage measuring unit each include a rising edge switch and a falling edge switch, and the rising edge switch samples the voltage across the divided voltage in response to the rising edge detecting signal And the falling edge switch can be switched to sample the voltage across the divided voltage in response to the falling edge detection signal.

The low-pass filter may include a voltage divider for weight-averaging the voltage sampled by the rising edge voltage measuring unit and the voltage sampled by the falling edge voltage measuring unit.

The voltage divider may include resistors having the same resistance value and the output of the voltage divider may be configured to output a voltage sampled by the rising edge voltage measuring unit and an average value of voltages sampled by the falling edge voltage measuring unit .

The rising edge extracting unit includes a NOT gate, a low-pass filter that receives the output of the NOT gate of the rising edge extracting unit, and a low-pass filter of the rising edge extracting unit. The rising edge extracting unit includes a rising edge extracting unit and a falling edge extracting unit. Wherein a voltage value of a PWM signal for controlling the three-phase motor is input to a NOT gate of the rising edge extracting unit, a NOT gate of the falling edge extracting unit, an OR gate, and a NAND gate of the falling edge extracting unit The NAND gate may NAND the PWM signal with the output of the low-pass filter of the rising edge extractor.

The falling edge extracting unit includes a NOT gate, a low bandpass filter receiving the output of the NOT gate of the falling edge extracting unit, and an OR gate receiving the output of the low band pass filter of the falling edge extracting unit. May OR the output of the low-pass filter of the falling edge extractor and the PWM signal.

The width of the output signal of the rising edge extracting unit may be greater than the width of the signal of the falling edge extracting unit.

Meanwhile, a three-phase motor control system according to an embodiment of the present invention includes a three-phase motor; A voltage measuring circuit for measuring a voltage across the voltage dividing resistor to measure a current flowing through the three-phase motor; A microcontroller unit including an ADC (Analog to Digital Converter) for outputting a PWM (Pulse Width Modulation) signal and converting a voltage value measured by the voltage measuring circuit into a digital value; A high voltage side switching unit connected to a power source; A low voltage side switching unit connected to the ground; And a pre-driver for receiving the PWM signal and applying a control signal to the high-voltage-side switching unit and the low-voltage-side switching unit based on the received PWM signal, the voltage measuring circuit comprising: An edge extraction unit for detecting a falling edge and outputting a rising edge detection signal and a falling edge detection signal; A sample and hold circuit for sampling a voltage across the split voltage at edge detection based on the rising edge detection signal and the falling edge detection signal; And a low pass filter that receives the signal output from the sample and hold circuit and passes the low frequency band of the output signal of the sample and holding circuit.

Also, the sample and holding circuit may include a rising edge voltage measuring unit and a falling edge voltage measuring unit.

Further, the rising edge voltage measuring unit and the falling edge voltage measuring unit each include a rising edge switch and a falling edge switch, and the rising edge switch samples the voltage across the divided voltage in response to the rising edge detecting signal And the falling edge switch can be switched to sample the voltage across the divided voltage in response to the falling edge detection signal.

The low-pass filter may include a voltage divider for weight-averaging the voltage sampled by the rising edge voltage measuring unit and the voltage sampled by the falling edge voltage measuring unit.

The voltage divider may include resistors having the same resistance value and the output of the voltage divider may be configured to output a voltage sampled by the rising edge voltage measuring unit and an average value of voltages sampled by the falling edge voltage measuring unit .

The rising edge extracting unit includes a NOT gate, a low-pass filter that receives the output of the NOT gate of the rising edge extracting unit, and a low-pass filter of the rising edge extracting unit. The rising edge extracting unit includes a rising edge extracting unit and a falling edge extracting unit. Wherein a voltage value of a PWM signal for controlling the three-phase motor is input to a NOT gate of the rising edge extracting unit, a NOT gate of the falling edge extracting unit, an OR gate, and a NAND gate of the falling edge extracting unit The NAND gate may NAND the PWM signal with the output of the low-pass filter of the rising edge extractor.

The falling edge extracting unit includes a NOT gate, a low bandpass filter receiving the output of the NOT gate of the falling edge extracting unit, and an OR gate receiving the output of the low band pass filter of the falling edge extracting unit. May OR the output of the low-pass filter of the falling edge extractor and the PWM signal.

The width of the output signal of the rising edge extracting unit may be greater than the width of the signal of the falling edge extracting unit.

Further, the classifying resistor may be connected to the low voltage side switching unit and the ground unit.

In addition, the dividing resistor may be connected to the motor and the portion to which the low-voltage-side switching unit and the high-voltage-side switching unit are connected.

Meanwhile, in a method of measuring current flowing in a three-phase motor according to an embodiment of the present invention, a voltage across both ends of a dividing resistor is measured using a voltage measuring circuit, The method comprising: detecting a rising edge and a falling edge of a PWM (Pulse Width Modulation) signal for controlling the three-phase motor to output a rising edge detection signal and a falling edge detection signal; Sampling a voltage across the split voltage at edge detection based on the rising edge detection signal and the falling edge detection signal; And outputting a weighted average of a voltage sampled at the rising edge detection signal and a voltage sampled based on the falling edge detection signal through a voltage divider and outputting the result; And converting the weighted average voltage to a digital value through an analog to digital converter (ADC).

Also, the voltage divider may include resistors having the same resistance value, and the weighted average output may output a simple averaged voltage value.

Therefore, according to the present invention, compared to the conventional three-phase motor control system in which the ADC trigger module is executed by a separate software module, the resource burden of the MCU is remarkably reduced and the resource burden of the saved MCU is controlled It can be used, which can be a great help to vehicle safety.

1 is a diagram showing a three-phase motor control system including a voltage measurement circuit according to an embodiment of the present invention.
2 (a) and 2 (b) are views showing the operation of the voltage measuring circuit according to the embodiment of the present invention.
3 is a diagram showing a voltage measuring circuit according to an embodiment of the present invention.
4 is a diagram illustrating an edge detector according to an embodiment of the present invention.
5 and 6 are timing charts showing the relationship between the edge detection signal and the PWM signal detected by the edge detection unit according to the embodiment of the present invention.
7 is a timing diagram illustrating an example of a voltage measured through a voltage measurement circuit according to an embodiment of the present invention.
8 is a diagram illustrating a three-phase motor control system including a voltage measurement circuit according to another embodiment of the present invention.
9 is a diagram illustrating an operation of a voltage measuring circuit according to another embodiment of the present invention.
10 is a timing chart showing a voltage applied to a voltage measuring circuit according to another embodiment of the present invention.
11 is a view showing a voltage measuring circuit according to another embodiment of the present invention.
12 is a diagram showing a conventional three-phase motor control system.
13 (a) and 13 (b) are diagrams showing the operation of a conventional three-phase motor control system.
14 is a timing chart showing the operation of a conventional three-phase motor control system.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, Is provided to fully inform the user. In addition, for convenience of explanation, components may be exaggerated or reduced in size.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it will be understood by those skilled in the art that the following embodiments are provided so that those skilled in the art will be able to fully understand the present invention, and that various changes and modifications may be made without departing from the scope of the present invention. It is not.

Hereinafter, a three-phase motor control system for measuring an average current value using the voltage measurement circuit 200 according to an embodiment of the present invention will be described with reference to FIG.

1, the three-phase motor control system 100 includes an MCU 110, a pre-driver 120, a high voltage side switching unit 130, a low voltage side switching unit 140, a three-phase motor 150, a shunt resistor 160, and a voltage measurement circuit 200. In this case, the high-voltage-side switching unit 130 is connected to the power source, and the low-voltage-side switching unit 140 is connected to the ground.

The MCU 110 transmits the PWM signal to the pre-driver 120 through the PWM transmission lines 115, 116, and 117 in order to drive the motor. As shown in FIG. 1, three transmission lines 115, 116 and 117 are used to transmit three PWM control signals for three-phase motor control and are input to the respective input units PWM_A, PWM_B and PWM_C .

The pre-driver 120 controls the high voltage side switching unit 130 and the low voltage side switching unit 140 based on the PWM signal received from the MCU 110 to provide current to the three-phase motor 150. More specifically, the pre-driver 120 includes a high-voltage-side gate control section 121 and a low-voltage-side gate control section 122 and controls the high-voltage-side switching section 130 and the low- A high voltage and / or a low voltage is applied to the gates of the switches 131 and 141 to turn on and / or off the switches 131 and 141.

On the other hand, a current flowing through the motor 150, the high-voltage switch 131 and the low-voltage switch 141 passes through the shunt resistor 160. At this time, the voltage measuring circuit 200 samples and holds the voltage across the classification resistor 160 at the moment of detecting the rising and falling edges of the PWM signal supplied through the PWM transmission lines 115, 116, and 117 .

The voltage measured by the voltage measuring circuit 200 is transmitted to the MCU 110 again. Preferably, the circuit may be configured to averify and output the voltages measured at the rising and falling edges in the voltage measuring circuit 200.

The MCU 110 receives the voltage measured by the voltage measuring circuit 200 through the analog input terminal 113 and then reads the digital value through the ADC 112. In this case, unlike the prior art, there is no need for a separate timing calculation for obtaining the average voltage, so the resource burden on the MCU can be greatly reduced.

2 (a) and 2 (b) are views showing the operation of the voltage measuring circuit 200 according to the embodiment of the present invention.

FIG. 2 (a) is a diagram showing the operation in the on-duty section. Both the high voltage side switch 131 and the low voltage side switch 141 are turned on so that the voltage supplied to the motor power supply flows through the high voltage side switch 131 and the low voltage side switch 141, (Not shown). In this case, the voltage across the dividing resistor 160 is measured by the voltage measuring circuit 200 and provided to the MCU 110.

2 (b) is a diagram showing the operation in the freewheeling period. In the free-wheeling section, the high voltage side switch 131 is turned off and the low voltage side switch 141 is turned on, thereby forming a closed circuit, and current flows. At this time, the free wheeling current does not flow in the dividing resistor 160.

Hereinafter, the specific configuration of the voltage measuring circuit 200 will be described in detail with reference to FIG.

The voltage measurement circuit 200 includes a buffer 220, a sample and hold circuit 230, a low pass filter circuit 250 and an edge extractor 400 and is connected to the analog input 113 in the MCU 110 And the measured voltage value is output.

The voltage across both ends of the classifying resistor 160 is amplified to a voltage within a range that can be read by the ADC 112 when read by the ADC 112 via the voltage measuring circuit 200 via the amplifier 165. [ This is because accurate measurement is difficult when the voltage value is converted into a digital value through the ADC 112 when the magnitude of the initially input voltage is too small.

The signal input through the amplifier 165 is input to the sample and hold circuit 230 via the input buffer 220. [

Meanwhile, the sample and hold circuit 230 may include a rising edge voltage measuring unit and a falling edge voltage measuring unit.

At this time, the rising edge voltage measuring section may include a rising edge switch 231, a holding resistor 233, a holding capacitor 234, and an output buffer 232. The falling edge voltage measuring unit may include a falling edge switch 235, a holding resistor 237, a holding capacitor 238, and an output buffer 236. [

The rising edge switch 231 receives the rising edge detection signal / V_ST_RED from the edge extraction unit 400. The rising edge switch 231 switches the input buffer 220 and the output buffer 232 to be connected without going through the holding resistor 233 when the input rising edge detection signal /V_ST_RED is, for example, a low voltage . The input buffer 220 may be omitted, in which case the rising edge switch 231 switches to be directly connected to the output of the amplifier 165.

The rising edge switch 231 switches the input buffer 220 to be connected to the output buffer 232 via the holding resistor 233 when the input rising edge detection signal /V_ST_RED is, for example, a high voltage . The input buffer 220 may be omitted. In this case, the rising edge switch 231 switches the output of the amplifier 165 and the output buffer 232 to be connected through the holding resistor 233.

When the rising edge switch 231 is switched so that the input buffer 220 and the output buffer 232 are connected to each other without passing through the holding resistor 233, the voltage across the classifying resistor 160 is amplified by the amplifier 165 and the buffer 220 is applied to the input terminal of the output buffer 232. That is, the voltage values at both ends of the classifying resistor 160 at the rising edge instant are sampled and output through the output buffer 232.

Conversely, when the rising edge switch 231 switches the input buffer 220 and the output buffer 233 to be connected through the holding resistor 233, the voltage value across the sampling resistor 160, which has been sampled, )do. In this case, the holding time is determined by the product of the holding resistor 233 and the holding capacitor 234. That is, when the product of the holding resistor 233 and the holding capacitor 234 increases, the holding time of the sampled voltage value becomes long, and in the opposite case, the holding time becomes short. During the above-described holding time, the sampled voltage value is held and output through the output buffer 232.

On the other hand, the falling edge switch 235 receives the falling edge detection signal / V_ST_FED from the edge extracting unit 400. The falling edge switch 235 switches the input buffer 220 and the output buffer 236 to be connected without going through the holding resistor 237 when the input falling edge detection signal /V_ST_FED is, for example, a low voltage . The input buffer 220 may be omitted, in which case the falling edge switch 235 switches to be directly connected to the output of the amplifier 165.

The falling edge switch 235 switches the input buffer 220 to be connected to the output buffer 236 through the holding resistor 237 when the input falling edge detection signal /V_ST_FED is, for example, a high voltage . The input buffer 220 may be omitted, in which case the falling edge switch 235 switches the output of the amplifier 165 and the output buffer 236 to be connected via the holding resistor 237.

When the falling edge switch 235 is switched so that the input buffer 220 and the output buffer 236 are connected to each other without passing through the holding resistor 237, the voltage across the classification resistor 160 is amplified by the amplifier 165 and the buffer 220 is applied to the input terminal of the output buffer 236. That is, the voltage values at both ends of the classifying resistor 160 at the falling edge instant are sampled and output through the output buffer 236.

Conversely, when the falling edge switch 235 switches the input buffer 220 and the output buffer 236 to be connected through the holding resistor 237, the voltage value across the sampling resistor 160, which has been sampled, )do. In this case, the holding time is determined by the product of the holding resistor 237 and the holding capacitor 238. [ That is, when the product of the holding resistor 237 and the holding capacitor 238 is large, the holding time of the sampled voltage value becomes long, and in the opposite case, the holding time becomes short. During the above-described holding time, the sampled voltage value is held and output through the output buffer 236. [

The resistors output through the output buffers 232 and 236 are output through the low pass filter circuit 250.

The low pass filter circuit 250 may be configured as an RC circuit, for example. Although the low-pass filter 250 is implemented through the resistors 251, 252 and 254 and the capacitors 254 and 255 in this embodiment, those skilled in the art will understand that implementing the low- It is possible.

Additionally, portions 251 and 252 of the resistors included in the low-pass filter 250 may also function as voltage dividers. The above described resistors 251 and 252 perform the function of a voltage divider and therefore the voltage values output from the output buffers 232 and 236 are controlled by resistors 251 and 252 which perform the function of a voltage divider Can be weighted averaged. In this case, when the voltage values of the resistors 251 and 252 performing the function of the voltage divider are the same, the average value of the voltage values output from the output buffers 232 and 236 is outputted.

Hereinafter, an edge extracting unit 400 according to an embodiment of the present invention will be described in detail with reference to FIG.

The edge extracting unit 400 according to the embodiment of the present invention includes a signal synthesizing unit 410, a rising edge detecting unit 420 and a falling edge detecting unit 430.

The signal synthesizing unit 410 is configured to synthesize the PWM signals received by the voltage measuring circuit 200 through the PWM transmission lines 115, 116, and 117 into one signal, and preferably uses an OR gate. In FIG. 4, an OR gate having three input units is represented. However, it is understood that a person skilled in the art can configure the signal synthesis unit 410 of the present embodiment through various configurations.

The output of the signal combiner 410 is input to the NOT gate 410 of the rising edge detector 420, the NAND gate 424 of the rising edge detector 420, the NOT gate of the falling edge detector 430, The falling edge detection unit 430, and the OR gate 434 of the falling edge detection unit 430.

4 and 5, the signal 520 passing through the NOT gate 421 and the low-pass filters 422 and 423 through the output of the signal combiner 410 is input to the direct signal combiner 410 A delay occurs relative to the signal 510 input to the NAND gate 424 directly. The NAND gate 424 performs a NAND operation on the output of the signal combiner 410 and the delayed signal V_OUT_LPF_RED to output a rising edge detection signal 530.

4 and 6, the signal 620 having passed through the NOT gate 431 and the low-pass filters 432 and 433 through the output of the signal combiner 410 is input to the direct signal combiner 410 A delay occurs relative to the signal 610 input to the direct OR gate 434. The OR gate 434 ORs the output of the signal combiner 410 and the delayed signal 620 to output a falling edge detection signal 630. [

However, the width of the rising edge detection signal 530 is preferably larger than the width of the falling edge detection signal 630. Because, if the voltage of the signal rises, there is a possibility of overshooting, so it is possible to measure a voltage higher than the voltage actually applied at the rising edge. Thus, the width of the rising edge detection signal 530 is made wider than the width of the falling edge detection signal 630 for accurate voltage measurement at the rising edge.

The width of these edge detection signals 530 and 630 may vary according to the time constant determined by the product of the resistors 422 and 433 and the capacitances 423 and 432 of the low pass filter.

Hereinafter, the operation of the sample and holder circuit 200 according to the embodiment of the present invention will be described in detail with reference to FIG.

When the PWM signal 700 is input to the pre-driver 120 through the PWM transmission lines 115, 116, and 117 in the MCU 110, the pre-driver 120 outputs the PWM signal 700 to the high voltage side switching unit 130 And the low voltage side switching unit 140 are driven. Then, current is supplied to the motor 150 through the high-voltage-side switching unit 130, and the supplied current flows again through the low-voltage switching unit 140 to the classifying resistor 160.

The voltage 710 across the breakdown resistor 160 is applied to the voltage measurement circuit 200 according to one embodiment of the present invention. The voltage 710 applied to the voltage measuring circuit 200 is applied to the rising edge voltage measuring unit and the falling edge voltage measuring unit.

The edge extraction unit 400 extracts the rising edge detection signal 720 and the falling edge detection signal 730 and outputs the rising edge detection signal 720 and the rising edge detection signal 730 to the rising edge switch 231 And the falling edge switch 235, respectively.

When the rising edge detection signal 720 is a low voltage, the rising edge switch 231 is directly connected to the output of the buffer 220, and the voltage across the falling resistor 160 is sampled at the rising edge. Conversely, when the rising edge detection signal 720 is at a high voltage, the voltage is held by the holding resistor 233 and the holding capacitance 236. [

Similarly, when the falling edge detection signal 730 is a low voltage, the voltage across the splitting resistor 160 is sampled when the falling edge switch 235 is directly connected to the output of the buffer 220 and on the falling edge. Conversely, when the falling edge detection signal 720 is at a high voltage, the voltage is held (held) by the holding resistor 237 and the holding capacitance 238.

The sampled and held voltages 740 and 760 at the rising and falling edges output a weighted averaged voltage value 750 by the voltage divider 251 and 252 in the low pass filter 250. Preferably, the resistors 251 and 252 have the same resistance value and output an average voltage value 750. The output voltage value is input to the analog input section 113 and the ADC 112 of the MCU 110 again.

Hereinafter, a method of measuring an average current value using the voltage measuring circuit 200 according to another embodiment of the present invention will be described with reference to FIGS. 8 to 10. FIG. In the description of Figs. 8 to 10, the description of the same portions as those of Figs. 1 to 7 is omitted for the sake of simplicity.

8, the three-phase motor control system 100 includes an MCU 110, a pre-driver 120, a high voltage side switching unit 130, a low voltage side switching unit 140, a motor 150, A shunt resistor 160, and a voltage measuring circuit 200. [

8, a voltage divider resistor 160-1 according to another embodiment of the present invention is installed between the motor 150 and the high voltage side switching part 130 and the low voltage side switching part 140. [

Since the switching unit 130 and the low voltage side switching unit 140 and the motor 150 are connected through the connector, the dividing resistor 160-1 is installed at the connector end.

9 (a) and 9 (b) are diagrams showing the operation of the voltage measuring circuit 200 according to another embodiment of the present invention.

9 (a) is a diagram showing the operation in the on-duty period. Voltage switch 131 and the low-voltage-side switch 141 are both turned on so that the voltage supplied to the motor power supply flows through the high-voltage-side switch 131 and the low-voltage- 160-1. In this case, the voltage across the dividing resistor 160-1 is measured by the voltage measuring circuit 200 and supplied to the MCU 110. [

9 (b) is a diagram showing the operation in the freewheeling period. In the free wheeling period, the high voltage side switch 131 is turned off, and only the low voltage side switch 141 is turned on so that a current flows while forming a closed circuit. However, in this embodiment, as shown in Fig. 10, since the freewheeling current flows in the dividing resistor 160-1, it is possible to measure the current flowing in the motor during the entire period in which the three-phase motor 150 is driven .

11 is a diagram illustrating a voltage measurement circuit 200 according to another embodiment of the present invention. In the description of Figs. 8 to 10, the description of the same portions as those of Figs. 1 to 7 is omitted for the sake of simplicity.

11, only one sampling and holding circuit 230 is provided in the voltage measuring circuit 200, and instead of using both the rising edge detection signal and the falling edge detection signal extracted from the edge extraction section 400, And drives the edge switch 231-1. Therefore, the voltage across both ends of the classifying resistor 160 or 160-1 can be measured without a separate voltage divider, and the circuit can be simplified with a simple configuration.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and similarities. Accordingly, the scope of the present invention should be construed as being limited to the embodiments described, and it is intended that the scope of the present invention encompasses not only the following claims, but also equivalents thereto.

100: Three-phase motor control system
200: Current measuring circuit
230: SAMPLE AND HOLDING CIRCUIT
250: Low-pass filter
400: edge extracting unit

Claims (20)

1. A voltage measuring circuit for measuring a voltage across a breaking resistor to measure a current flowing in a three-phase motor,
An edge extraction unit for detecting a rising edge and a falling edge of a PWM (Pulse Width Modulation) signal for controlling the three-phase motor to output a rising edge detection signal and a falling edge detection signal;
A sample and hold circuit for sampling a voltage across the split voltage at edge detection based on the rising edge detection signal and the falling edge detection signal; And
And a low pass filter for receiving a signal output from the sample and hold circuit and passing the low frequency signal through the low band of the output signal of the sample and holding circuit
Voltage measuring circuit.
The method according to claim 1,
Wherein the sample and holding circuit includes a rising edge voltage measuring unit and a falling edge voltage measuring unit,
Voltage measuring circuit.
3. The method of claim 2,
The rising edge voltage measuring unit and the falling edge voltage measuring unit each include a rising edge switch and a falling edge switch,
Wherein the rising edge switch is switched to sample a voltage across the classification voltage in response to the rising edge detection signal,
Wherein the falling edge switch is switched to sample a voltage across the split voltage in response to the falling edge detection signal,
Voltage measuring circuit.
The method of claim 3,
Wherein the low-pass filter includes a voltage divider that weight-averages a voltage sampled by the rising edge voltage measuring unit and a voltage sampled by the falling edge voltage measuring unit,
Voltage measuring circuit.
5. The method of claim 4,
Wherein the voltage divider includes resistors having the same resistance value and the output of the voltage divider is configured to output an average value of a voltage sampled in the rising edge voltage measuring unit and a voltage sampled in the falling edge voltage measuring unit,
Voltage measuring circuit.
The method according to claim 1,
Wherein the edge extracting unit includes a rising edge extracting unit and a falling edge detecting unit,
Wherein the rising edge extracting unit includes a NOT gate, a low band pass filter receiving the output of the NOT gate of the rising edge extracting unit, and a NAND gate receiving the output of the low band pass filter of the rising edge extracting unit,
The voltage value of the PWM signal for controlling the three-phase motor is input to the NOT gate of the rising edge extracting unit, the NOT gate of the falling edge extracting unit, the OR gate, and the input unit of the NAND gate,
Wherein the NAND gate NANDs an output of the low-pass filter of the rising edge extractor with a PWM signal to output the rising edge detection signal,
Voltage measuring circuit.
The method according to claim 6,
Wherein the falling edge extracting unit includes a NOT gate, a low band pass filter receiving the output of the NOT gate of the falling edge extracting unit, and an OR gate receiving the output of the low band pass filter of the falling edge extracting unit,
Wherein the OR gate ORs an output of the low-pass filter of the falling edge extractor with a PWM signal to output the falling edge detection signal,
Voltage measuring circuit.
The method according to claim 6,
Wherein the width of the rising edge detection signal is greater than the width of the falling edge detection signal,
Voltage measuring circuit.
Three - phase motor;
A voltage measuring circuit for measuring a voltage across the voltage dividing resistor to measure a current flowing through the three-phase motor;
A microcontroller unit including an ADC (Analog to Digital Converter) for outputting a PWM (Pulse Width Modulation) signal and converting a voltage value measured by the voltage measuring circuit into a digital value;
A high voltage side switching unit connected to a power source;
A low voltage side switching unit connected to the ground; And
And a pre-driver that receives the PWM signal and applies a control signal to the high voltage side switching unit and the low voltage side switching unit based on the received PWM signal,
The voltage measuring circuit includes:
An edge extraction unit for detecting a rising edge and a falling edge of the PWM signal and outputting a rising edge detection signal and a falling edge detection signal;
A sample and hold circuit for sampling a voltage across the split voltage at edge detection based on the rising edge detection signal and the falling edge detection signal; And
And a low pass filter for receiving a signal output from the sample and hold circuit and passing the low frequency signal through the low band of the output signal of the sample and holding circuit
Three - phase motor control system.
10. The method of claim 9,
Wherein the sample and holding circuit includes a rising edge voltage measuring unit and a falling edge voltage measuring unit,
Three - phase motor control system.
11. The method of claim 10,
The rising edge voltage measuring unit and the falling edge voltage measuring unit each include a rising edge switch and a falling edge switch,
Wherein the rising edge switch is switched to sample a voltage across the classification voltage in response to the rising edge detection signal,
Wherein the falling edge switch is switched to sample a voltage across the split voltage in response to the falling edge detection signal,
Three - phase motor control system.
12. The method of claim 11,
Wherein the low-pass filter includes a voltage divider that weight-averages a voltage sampled by the rising edge voltage measuring unit and a voltage sampled by the falling edge voltage measuring unit,
Three - phase motor control system.
13. The method of claim 12,
Wherein the voltage divider includes resistors having the same resistance value and the output of the voltage divider is configured to output an average value of a voltage sampled in the rising edge voltage measuring unit and a voltage sampled in the falling edge voltage measuring unit,
Three - phase motor control system.
10. The method of claim 9,
Wherein the edge extracting unit includes a rising edge extracting unit and a falling edge detecting unit,
Wherein the rising edge extracting unit includes a NOT gate, a low band pass filter receiving the output of the NOT gate of the rising edge extracting unit, and a NAND gate receiving the output of the low band pass filter of the rising edge extracting unit,
The voltage value of the PWM signal for controlling the three-phase motor is input to the NOT gate of the rising edge extracting unit, the NOT gate of the falling edge extracting unit, the OR gate, and the input unit of the NAND gate,
Wherein the NAND gate NANDs an output of the low-pass filter of the rising edge extractor with a PWM signal to output the rising edge detection signal,
Three - phase motor control system.
15. The method of claim 14,
Wherein the falling edge extracting unit includes a NOT gate, a low band pass filter receiving the output of the NOT gate of the falling edge extracting unit, and an OR gate receiving the output of the low band pass filter of the falling edge extracting unit,
Wherein the OR gate ORs an output of the low-pass filter of the falling edge extractor with a PWM signal to output the falling edge detection signal,
Three - phase motor control system.
15. The method of claim 14,
Wherein the width of the rising edge detection signal is greater than the width of the falling edge detection signal,
Three - phase motor control system.
10. The method of claim 9,
Voltage side switching unit and the grounding unit,
Three - phase motor control system.
10. The method of claim 9,
Wherein the voltage dividing resistor is connected to the part to which the low voltage side switching part and the high voltage side switching part are connected,
Three-phase motor control system
A method of measuring a current flowing through a three-phase motor using a voltage measuring circuit to measure a voltage across a dividing resistor and using a voltage across the dividing voltage,
Outputting a rising edge detection signal and a falling edge detection signal by detecting a rising edge and a falling edge of a PWM (Pulse Width Modulation) signal for controlling the three-phase motor;
Sampling a voltage across the split voltage at edge detection based on the rising edge detection signal and the falling edge detection signal; And
Outputting a weighted average of a voltage sampled at the rising edge detection signal and a voltage sampled based on the falling edge detection signal through a voltage divider; And
And converting the weighted average voltage to a digital value via an analog to digital converter (ADC).
A method for measuring current flowing in a three-phase motor. 20. The method of claim 19,
Wherein the voltage divider is composed of resistors having the same resistance value,
Wherein the step of outputting the weighted average comprises:
A method for measuring current flowing in a three-phase motor.

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