CN103812476B - Sine Wave Pulse Width Modulation Controller - Google Patents

Abstract

The invention relates to a sine wave pulse width modulation controller, which comprises an edge detection unit, a register, an angle increasing unit, a sine wave calculation unit, a multiplication unit and a sine wave output unit, wherein the edge detection unit receives a feedback input signal of an external electric device, to generate edge signal, the buffer stores and outputs parameter signal, the angle increasing unit receives edge signal and parameter signal, determines the number of pulse width modulation cycle to generate angle signal, the sine wave calculating unit receives and generates sine wave calculated value by recursive algorithm of coordinate rotation digital calculation according to the angle signal, the multiplying unit receives sine wave calculated value and multiplies the amplitude signal to generate pulse width signal, the sine wave output unit receives the voltage signal to generate a driving signal, so as to drive an external electric device to generate a terminal voltage with a sine wave on the action element.

Description

Sine Wave Pulse Width Modulation Controller

technical field

The invention relates to a pulse width modulation controller, especially for generating a sine wave pulse width modulation driving signal.

Background technique

In the field of motors and electronics, especially in the field of power conversion, high-precision sine waves are required. However, the existing technology generally stores a large number of sine waves in the memory in the form of a look-up table, and when used, according to the required Read the corresponding sine value in memory.

However, the disadvantages of the prior art are that a large amount of memory is required, and the improvement of the accuracy is rather limited. Therefore, there is a need for a sine wave pulse width modulation controller that utilizes an appropriate algorithm for calculation to save memory and simplify the overall system architecture, thereby solving the above-mentioned problems in the prior art.

Contents of the invention

The main purpose of the present invention is to provide a sine wave pulse width modulation controller, which includes an edge detection unit, a register, an angle increment unit, a sine wave calculation unit, a multiplication unit and a sine wave output unit for driving external electrical devices A sine wave is generated, wherein the external electrical device includes at least one action element.

The edge detection unit receives the feedback input signal of the external electrical device, and performs edge detection to generate an edge signal. The register stores at least one parameter, and at least outputs the parameter signal, the amplitude signal and the operation mode, and the parameter of the register is determined by The system defaults or is set by the user. The angle increment unit receives the edge signal and the parameter signal to determine the number of pulse width modulation cycles, and then generates the angle signal.

The sine wave calculation unit receives and performs a recursive algorithm for coordinate rotation digital calculation based on the angle signal, and then generates a sine wave calculation value. The multiplication unit receives the sine wave calculation value and performs multiplication operation with the amplitude signal from the buffer to generate a pulse width signal. The sine wave output unit receives the pulse width signal and generates a plurality of sine wave driving signals in a pulse width modulation manner.

Therefore, the sine wave driving signal generated by the sine wave output unit can drive the external electrical device to generate a sine wave terminal voltage on the operating element.

Description of drawings

Fig. 1 is the schematic diagram showing the sine wave pulse width modulation controller of the present invention;

2 is a schematic diagram of a full-bridge electrical device driven by a sine wave pulse width modulation controller of the present invention;

3 is a schematic diagram of a half-bridge electrical device driven by a sine wave pulse width modulation controller of the present invention;

Fig. 4 is the schematic diagram showing CORDIC recursive algorithm among the present invention;

FIG. 5 is a diagram showing output waveforms of the sine wave PWM controller of the present invention.

Wherein, the reference signs are explained as follows:

10 edge detection unit

20 buffers

30 Angle Incremental Units

40 sine wave calculation units

50 multiply units

60 sine wave output unit

70 External electrical installations

AM amplitude signal

AN angle signal

C filter capacitor

ED edge signal

FB feedback input signal

L action element

L1 filter inductor

MD mode of operation

PR parameter signal

SQ1 first sine wave drive signal

SQ2 second sine wave drive signal

SQ3 The third sine wave driving signal

SQ4 The fourth sine wave drive signal

ST Calculated value of sine wave

SW pulse width signal

T1 first drive transistor

T2 second drive transistor

T3 third drive transistor

T4 Fourth drive transistor

VH high voltage power cord

VL low voltage power cord

VO terminal voltage

detailed description

The implementation of the present invention will be described in more detail below with reference to the figures and symbol numbers, so that those skilled in the art can implement it after studying this specification.

Referring to FIG. 1 , it is a schematic diagram of a sine wave pulse width modulation controller of the present invention. As shown in FIG. 1, the sine wave pulse width modulation (Sine Pulse Width Modulation, SIN PWM) controller of the present invention includes an edge detection unit 10, a buffer 20, an angle increment unit 30, a sine wave calculation unit 40, and a multiplication unit 50 and the sine wave output unit 60, in order to specifically realize the recursive algorithm of the coordinate rotation digital calculation (Coordinate Rotation Digital Computer, CORDIC), drive the external electrical device 70 to generate the sine wave, and further, the sine wave pulse width of the present invention The modulation controller mainly forms a feedback loop, which can provide stable feedback control to the external electrical device 70 .

The aforementioned external electrical device 70 may include the devices shown in FIG. 2 or FIG. 3 , which are full-bridge electrical devices and half-bridge electrical devices, respectively. However, it should be noted that the device shown in FIG. 2 or FIG. 3 is only used to illustrate the technical features of the present invention, and is not intended to limit the scope of the present invention.

First, the full-bridge electrical device in FIG. 2 is described, which mainly includes a first drive transistor T1, a second drive transistor T2, a third drive transistor T3, a fourth drive transistor T4, an operating element L, a filter inductor L1 and a filter capacitor C. Wherein the first drive transistor T1, the second drive transistor T2, the third drive transistor T3 and the fourth drive transistor T4 are respectively controlled by the first sine wave drive signal SQ1, the second sine wave drive signal SQ2, the third sine wave drive signal SQ3 and Driven by the fourth sine wave drive signal SQ4. The first driving transistor T1 and the second driving transistor T2 are connected in series between the high voltage power line VH and the low voltage power line VL. Similarly, the third driving transistor T3 and the fourth driving transistor T4 are connected in series between the high voltage power line VH and the low voltage power line VL. In addition, the filter inductor L1 and the filter capacitor C are connected in series to the series connection point of the first driving transistor T1 and the second driving transistor T2 and the series connection point of the third driving transistor T3 and the fourth driving transistor T4, and the operating element L is when As a load, and connected in parallel to the filter capacitor C.

Referring to FIG. 3, the half-bridge electrical device is a full-bridge structure similar to that of FIG. The filter capacitor C, wherein the first drive transistor T1 and the second drive transistor T2 are respectively driven by the first sine wave drive signal SQ1 and the second sine wave drive signal SQ2, the first drive transistor T1 and the second drive transistor T2 are connected in series and the second A capacitor C1 and a second capacitor C2 are connected in series and further connected between the high voltage power line VH and the low voltage power line VL. The filter inductor L1 and the filter capacitor C are connected in series and connected to the series connection point of the first drive transistor T1 and the second drive transistor T2 and one end of the operating element L, and the operating element L is connected in parallel with the filter capacitor C, and the other end of the operating element L is connected to To the series connection point of the first capacitor C1 and the second capacitor C2.

The terminal voltage VO of the above action element L can pass through a voltage attenuator (not shown) to form the feedback input signal FB in Figure 1, or the current flowing through the action element L can be used to form a feedback signal FB through a current attenuator (not shown). grant input signal FB.

In FIG. 1, the edge detection unit 10 of the sine wave pulse width modulation controller receives the feedback input signal FB from the external electrical device 70, and performs edge detection to determine whether the current waveform is a positive half cycle or a negative half cycle, and then An edge signal ED is generated. The register 20 stores at least one parameter, and at least outputs the parameter signal PR, the amplitude signal AM, and the operation mode MD, and the parameters of the register 20 can be preset by the system or set by the user, and can include incremental input angles (such as 1 ° or 1.5°), the amplitude of the sine wave, the dead time (dead time), and the start control bit of the sine wave width modulation.

The angle increment unit 30 receives the edge signal ED from the edge detection unit 10 and the parameter signal PR from the register 20 to determine the number of PWM cycles in a half cycle (PWM cycles), and then generate the angle signal AN. For example, when the parameter signal PR is 1, there are 180 PWM cycles per half cycle, and when the parameter signal PR is 0.5, there are 360 PWM cycles per half cycle.

The sine wave calculation unit 40 receives and performs right shift processing according to the angle signal AN of the angle increment unit 30 to implement the recursive algorithm of CORDIC to generate a sine wave calculation value ST. The following briefly describes the recursive algorithm of CORDIC.

The current amplitude of the sine wave, sin(θ), can be determined by the amplitude of the previous angle. Therefore, starting from the angle of 0°, the amplitude of the next angle can be obtained with evenly distributed angles. Specifically, referring to FIG. 4 , two points in the plane Cartesian coordinates have coordinates (X1, Y1) and (X2, Y2) respectively, expressed as follows:

(X1, Y1) = (cos(θ1), sin(θ1))

(X2, Y2) = (cos(θ2), sin(θ2))

Among them, θ1 and θ2 are the angles of the coordinates (X1, Y1) and (X2, Y2) in polar coordinates respectively, and as shown in the figure, the angle θ is the difference between θ2 and θ1 (θ=θ2-θ1), therefore, the coordinates (X2, Y2) can be expressed by coordinates (X1, Y1) as follows:

X2＝X1*cos(θ)-Y1*sin(θ)

Y2＝Y1*sin(θ)+Y1*cos(θ)

or further organized into:

X2＝cos(θ)*[X1-Y1*tan(θ)]

Y2＝cos(θ)*[X1*tan(θ)+Y1]

The general expression for the above coordinates is as follows:

Xn＝cos(θn)*[X _n-1 -Y _n-1 *tan(θn)]

Yn＝cos(θn)*[X _n-1 *tan(θn)+Y _n-1 ]

Where n is a non-negative integer (n=0, 1, 2, 3, etc.), and θn is the nth coordinate (Xn, Yn) relative to the previous n-1th coordinate (Xn-1, Yn-1 ), and the initial value of θn(n=0) is 0°, and then when n=1, 2, and 3, the θn angles are 45°, 26.565°, and 14.0362° respectively, that is, θn=tan ^{- 1} (1/2 ^n-1 ).

Therefore, the specific operation of the sine wave calculation unit 40 is to calculate tan(θn) by shifting the current value by one bit according to the CORDIC recursive algorithm, and the sine wave calculation value ST generated by the sine wave calculation unit 40 refers to tan( θn), that is, 1/2 ^n-1 .

The multiplication unit 50 receives the sine wave calculation value ST from the sine wave calculation unit 40, and performs a multiplication operation with the amplitude signal AM from the buffer 20 to generate a pulse width signal SW, which is received by the sine wave output unit 60 in PWM mode Generate the first sine wave drive signal SQ1, the second sine wave drive signal SQ2, the third sine wave drive signal SQ3 and the fourth sine wave drive signal SQ4, so as to drive the external electrical device 70 to generate a sine wave terminal voltage VO, as shown in Figure 5 shown. It should be noted that the half-bridge electrical device in FIG. 3 needs to be driven by the first sine wave driving signal SQ1 and the second sine wave driving signal SQ2 .

Therefore, the feature of the present invention is mainly to use the sine wave calculation unit shifted to the right by one bit to calculate the tangent value (tan) of the next angle for subsequent generation of the required sine wave drive signal, which can avoid using a large number of look-up tables By storing trigonometric function values with high precision, memory is saved, the overall structure can be simplified, and the operation speed and efficiency can be improved.

The above descriptions are only preferred embodiments for explaining the present invention, and are not intended to limit the present invention in any form. Therefore, any modification or change related to the present invention made under the same spirit of the invention should still be included in the scope of protection intended by the present invention.

Claims (6)

1. A sine wave pulse width modulation controller, used to drive an external electrical device, and the external electrical device includes at least one action element, characterized in that the sine wave pulse width modulation controller includes: An edge detection unit receives a feedback input signal from the external electrical device, and performs edge detection to generate an edge signal; A register storing at least one parameter, and at least outputting a parameter signal, an amplitude signal and an operation mode, and the parameter of the register is preset by the system or set by the user; an angle increasing unit, receiving the edge signal and the parameter signal to determine the number of pulse width modulation (Pulse Width Modulation, PWM) cycles (cycles), and then generate an angle signal; A sine wave calculation unit receives and performs right displacement processing according to the angle signal, so as to realize the recursive algorithm of Coordinate Rotation Digital Computer (CORDIC), and then generate a sine wave calculation value; a multiplication unit, receiving the calculated value of the sine wave, and performing a multiplication operation with the amplitude signal from the register to generate a pulse width signal; and A sine wave output unit, which receives the pulse width signal and generates a first sine wave drive signal, a second sine wave drive signal, a third sine wave drive signal and a fourth sine wave drive signal in PWM mode, so as to drive The external electrical device generates a terminal voltage with a sine wave on the operating element. 2. The sine wave pulse width modulation controller as claimed in claim 1, wherein the external electrical device further comprises a first driving transistor, a second driving transistor, a third driving transistor, a fourth driving transistor transistor, a filter inductor and a filter capacitor, and the first drive transistor, the second drive transistor, the third drive transistor and the fourth drive transistor are respectively driven by the first sine wave drive signal and the second sine wave signal, the third sine wave drive signal and the fourth sine wave drive signal, the first drive transistor and the second drive transistor are connected in series between a high voltage power supply line and a low voltage power supply line, the third The drive transistor and the fourth drive transistor are connected in series between the high-voltage power supply line and the low-voltage power supply line, and the filter inductor and the filter capacitor are connected in series to one of the first drive transistor and the second drive transistor. A series connection point and a series connection point of the third drive transistor and the fourth drive transistor, and the action element is used as a load and connected in parallel to the filter capacitor. 3. The sine wave pulse width modulation controller according to claim 1, characterized in that, the feedback input signal is formed by the terminal voltage of the operating element through a voltage attenuator, or is formed by a voltage flowing through the operating element The current is formed through a current attenuator. 4. A sine wave pulse width modulation controller for driving an external electrical device, and the external electrical device includes at least one action element, characterized in that the sine wave pulse width modulation controller includes: An edge detection unit receives a feedback input signal from the external electrical device, and performs edge detection to generate an edge signal; A register storing at least one parameter, and at least outputting a parameter signal, an amplitude signal and an operation mode, and the parameter of the register is preset by the system or set by the user; an angle increasing unit, receiving the edge signal and the parameter signal to determine the number of pulse width modulation (Pulse Width Modulation, PWM) cycles (cycles), and then generate an angle signal; A sine wave calculation unit receives and performs right displacement processing according to the angle signal, so as to realize the recursive algorithm of Coordinate Rotation Digital Computer (CORDIC), and then generate a sine wave calculation value; a multiplication unit, receiving the calculated value of the sine wave, and performing a multiplication operation with the amplitude signal from the register to generate a pulse width signal; and A sine wave output unit, which receives the pulse width signal and generates a first sine wave drive signal and a second sine wave drive signal in PWM mode, so as to drive the external electrical device and generate a sine wave terminal on the action element Voltage. 5. The sine wave pulse width modulation controller as claimed in claim 4, wherein the external electrical device further comprises a first drive transistor, a second drive transistor, a first capacitor, a second capacitor, A filter inductor and a filter capacitor, and the first drive transistor and the second drive transistor are respectively driven by the first sine wave drive signal and the second sine wave drive signal, the first drive transistor and the second drive transistor connected in series between a high-voltage power line and a low-voltage power line, the first capacitor and the second capacitor are connected in series between the high-voltage power line and the low-voltage power line, and one end of the filter inductor is connected to A series connection point of the first drive transistor and the second drive transistor, the other end of the filter inductor is connected to one end of the filter capacitor and one end of the action element, and the other end of the filter capacitor is connected to one end of the action element The other end is connected to a series junction of the first capacitor and the second capacitor, and the action element is connected in parallel to the filter capacitor. 6. The sine wave pulse width modulation controller as claimed in claim 4, characterized in that, the feedback input signal is formed by the terminal voltage of the operating element through a voltage attenuator, or is formed by a voltage flowing through the operating element The current is formed through a current attenuator.