Motor simulator

Abstract

The motor simulator provided by the invention is used for solving the technical problems of large motor weight, large noise, high cost and large occupied area when a frequency converter motor load is subjected to a loading test. A capacitor C1 of the motor simulator is connected in parallel with a three-phase bridge circuit; three inductors of the inductor unit L1 are respectively connected with the output end of the three-phase bridge circuit; the input end of the phase voltage detection module is connected with frequency converter output voltage, and the output end is sequentially connected with the waveform shaping capture module and the switching tube waveform decomposition module; the input end of the current regulator is used for receiving a detection current signal and a set current signal, and the output end of the current regulator is sequentially connected with the duty ratio regulation module / delay angle regulation module and the PWM wave sending module; and the output ends of the switching tube waveform decomposition module and the PWM generator module are respectively connected with the logic AND gate module, and the logic AND gate module outputs signals to drive each switching tube of the three-phase bridge circuit to act so as to realize real-time tracking control of the motor simulator.

Description

[0001] This application is a divisional application of the invention patent with application number 202210687504X.

[0002] Filing date of original application: June 16, 2022.

[0003] The title of the invention of the original application: A motor simulator and its real-time tracking control method. Technical Field

[0004] The invention relates to a frequency converter motor load, and in particular to a motor simulator and a real-time tracking control method thereof. Background Art

[0005] During the factory test of the inverter or new energy vehicle drive (hereinafter referred to as the inverter), a loading test with a motor load is required. Due to the heavy weight and noise of the motor, and the need for an external eddy current brake or a towing motor for motor loading, the cost is high and the area occupied is large. Summary of the invention

[0006] The purpose of the present invention is to solve the technical problems of heavy motor weight and high noise during the inverter motor load test and high cost and large floor space caused by the motor loading method, and to provide a motor simulator and a real-time tracking control method thereof.

[0007] In order to achieve the above-mentioned invention object, the technical solution provided by the present invention is:

[0008] A motor simulator, which is special in that it includes a three-phase bridge circuit, a capacitor C1, an inductor unit L1, a phase voltage detection module, a waveform shaping capture module, a switch tube waveform decomposition module, a current regulator, a duty cycle adjustment module, a delay angle adjustment module, a PWM wave generation module and a logic AND gate module;

[0009] The capacitor C1 is connected in parallel with the three-phase bridge circuit;

[0010] The inductor unit L1 includes three inductors, one end of each of which is connected to the three output ends of the three-phase bridge circuit respectively, and the other ends of each of which are used to connect to the three-phase output ends of the inverter to be detected and to the input end of the phase voltage detection module respectively; the output end of the phase voltage detection module is connected to the waveform shaping capture module and the switch tube waveform decomposition module in sequence, the phase voltage detection module is used to collect the output voltage of the inverter, and detect the rising edge and falling edge of the collected output voltage of the inverter through the waveform shaping capture module, and decompose the drive waveform a of each switch tube of the inverter through the switch tube waveform decomposition module;

[0011] The current regulator is used to receive the detection current signal of the inductor unit L1 and adjust it with the set current signal;

[0012] The output end of the current regulator is connected to the duty cycle adjustment module, and the output end of the duty cycle adjustment module is connected to the PWM wave generation module; or, the output end of the current regulator is connected to the delay angle adjustment module, and the output end of the delay angle adjustment module is connected to the PWM wave generation module;

[0013] The PWM wave generating module is used to obtain the PWM wave generating waveform b of the motor simulator;

[0014] The output end of the switch tube waveform decomposition module and the output end of the PWM wave generation module are respectively connected to the input end of the logic AND gate module, and the output end of the logic AND gate module is connected to the three-phase bridge circuit; the logic AND gate module is used to perform a logic AND operation on the PWM wave generation waveform b of the motor simulator and the drive waveform a of each switch tube of the inverter to generate an output drive waveform c to drive the corresponding switch tube of the three-phase bridge circuit to work.

[0015] Based on the above motor simulator, the present invention also provides a real-time tracking control method of the motor simulator, which is special in that it includes the following steps:

[0016] 1) Detect the drive waveform a of each switch tube of the inverter

[0017] 1.1) Collect the inverter output voltage through the phase voltage detection module;

[0018] 1.2) Detect the rising and falling edges of the collected inverter output voltage through the waveform shaping capture module;

[0019] 1.3) Decompose the waveform through the switch tube waveform decomposition module to obtain the drive waveform a of each switch tube in the three-phase bridge inverter circuit inside the inverter;

[0020] 2) Obtain the PWM waveform b of the motor simulator

[0021] 2.1) The current regulator receives the detection current signal of the inductor unit L1 and adjusts it with the set current signal;

[0022] 2.2) The duty cycle of the PWM wave generator module is adjusted by the duty cycle adjustment module to achieve the current regulation of the inductor unit L1, or the time ts by which the motor simulator output voltage phase lags the inverter output voltage phase is adjusted by the delay angle adjustment module to achieve the current regulation of the inductor unit L1;

[0023] 2.3) Obtain the PWM wave waveform b of the motor simulator through the PWM wave module;

[0024] 3) The PWM wave waveform b of the motor simulator is ANDed with the drive waveform a of the corresponding switch tube of the inverter through the logic AND gate module to obtain the output drive waveform c, which is used to control the operation of the corresponding switch tube of the three-phase bridge circuit (1) to achieve real-time tracking control of the motor simulator.

[0025] Furthermore, in step 2.2), the current regulation of the inductor unit L1 is realized by adjusting the duty cycle of the PWM wave generating module as follows:

[0026] The PWM wave module frequency of the motor simulator is set to be more than 2 times higher than the switching frequency of the inverter. At the same time, when the output voltage phase of the motor simulator lags behind the output voltage phase of the inverter by time ts=0, the current regulation of the inductor unit L1 is achieved by adjusting the duty cycle of the PWM wave module by the following formula:

[0027]

[0028] Wherein, Vb is the output voltage amplitude of the inverter, Dm is the duty cycle of the PWM wave generating module, L is the inductance value of the inductor unit L1, ω is the angular frequency of the AC voltage, and j is the sign of the complex imaginary part.

[0029] Furthermore, in step 2.2), the current regulation of the inductor unit L1 is achieved by adjusting the time ts by which the motor simulator output voltage phase lags behind the inverter output voltage phase, specifically:

[0030] When the time ts that the motor simulator output voltage phase lags behind the inverter output voltage phase is set to ≥ 0, the current regulation of the inductor unit L1 is achieved by adjusting the time ts that the motor simulator output voltage phase lags behind the inverter output voltage phase through the following formula:

[0031]

[0032] Wherein, Vb is the output voltage amplitude of the inverter, L is the inductance value of the inductor unit L1, t is time, ω is the angular frequency of the AC voltage, and j is the sign of the complex imaginary part.

[0033] Beneficial effects of the present invention:

[0034] 1. The motor simulator provided by the present invention has a simple circuit structure. During testing, the simulated motor load of the present invention has significantly reduced mass and noise compared to traditional motor loads. Moreover, the simulated motor load does not require an external eddy current brake or a towing motor, so it occupies a small area and reduces the overall testing cost.

[0035] 2. The present invention provides a real-time tracking control method for a motor simulator. The motor simulator follows the output of the inverter in each switching cycle of the inverter, so that the voltage phases across the inductor L1 are basically consistent. Current control is achieved by adjusting the voltage difference across the inductor L1, so that the motor simulator can complete real-time tracking control. There is no need to adopt the traditional motor load model calculation method, and the control method is simple and reliable.

[0036] 3. The present invention provides a real-time tracking control method for a motor simulator, which realizes current regulation of the inductor unit L1 by adjusting the duty cycle of the PWM wave generating module. The control method is simple and can perform current regulation in real time according to customer needs.

[0037] 4. The present invention provides a real-time tracking control method for a motor simulator, which realizes the current regulation of the inductor unit L1 by adjusting the time ts that the output voltage phase of the motor simulator lags behind the output voltage phase of the inverter. It can adjust the current amplitude of the inductor unit L1 and the current phase angle of the inductor unit L1 to realize the regulation of active current. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of the circuit structure of an embodiment of a motor simulator of the present invention;

[0039] Figure 2 An equivalent diagram of a circuit system of a motor simulator embodiment of the present invention;

[0040] Figure 3 It is a schematic diagram of the “AND” operation in step 3) of an embodiment of a real-time tracking control method for a motor simulator of the present invention.

[0041] The specific figures are:

[0042] 1-three-phase bridge circuit; 2-phase voltage detection module; 3-waveform shaping and capturing module; 4-switch tube waveform decomposition module; 5-current regulator; 6-duty cycle adjustment module; 7-delay angle adjustment module; 8-PWM wave generation module; 9-logic AND gate module; 10-frequency converter. DETAILED DESCRIPTION

[0043] In order to make the advantages and features of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] The present invention provides a motor simulator, such as Figure 1As shown, it includes a three-phase bridge circuit 1, a capacitor C1, an inductor unit L1, a phase voltage detection module 2, a waveform shaping and capturing module 3, a switch tube waveform decomposition module 4, a current regulator 5, a duty cycle adjustment module 6, a delay angle adjustment module 7, a PWM wave generation module 8 and a logic AND gate module 9. The capacitor C1 is connected in parallel with the three-phase bridge circuit 1; the inductor unit L1 includes three inductors, one end of the three inductors is respectively connected to the three output ends of the three-phase bridge circuit 1, and the other ends of the three inductors are respectively used to connect the three-phase output ends of the inverter 10 to be detected, and are connected to the input end of the phase voltage detection module 2; the output end of the phase voltage detection module 2 is sequentially connected to the waveform shaping capture module 3 and the switch tube waveform decomposition module 4, the phase voltage detection module 2 is used to collect the output voltage of the inverter, and detect the rising edge and falling edge of the collected output voltage of the inverter 10 through the waveform shaping capture module 3, and decompose the drive waveform a of each switch tube of the inverter 10 through the switch tube waveform decomposition module 4; the current regulator 5 is used to receive the detection current signal of the inductor unit L1 and adjust it with the set current signal, and the output end of the current regulator 5 A duty cycle adjustment module 6 is connected to adjust the duty cycle of the current signal, and the output end of the duty cycle adjustment module 6 is connected to a PWM wave generation module 8; or, the output end of the current regulator 5 is connected to a delay angle adjustment module 7 to adjust the delay angle of the current signal, and the output end of the delay angle adjustment module 7 is connected to a PWM wave generation module 8; the PWM wave generation module 8 is used to obtain the PWM wave generation waveform b of the motor simulator; the output end of the switch tube waveform decomposition module 4 and the output end of the PWM wave generation module 8 are respectively connected to the input end of a logic AND gate module 9, and the output end of the logic AND gate module 9 is connected to a three-phase bridge circuit 1; the logic AND gate module 9 is used to perform a logic AND operation on the PWM wave generation waveform b of the motor simulator and the drive waveform a of each switch tube of the inverter to generate an output drive waveform c to drive the corresponding switch tube of the three-phase bridge circuit 1 to work.

[0045] Circuit working principle: Figure 2 As shown, it is a system equivalent diagram of a motor simulator circuit diagram of the present invention. ACb is the equivalent output AC source of the inverter 10, and its output voltage is Vb*cosωt; ACm is the equivalent output AC source of the motor simulator, and its output voltage is Vm*cosω(t-ta); wherein Vb is the output voltage amplitude of the inverter 10, Vm is the output voltage amplitude of the motor simulator, ω is the AC voltage angular frequency, and ta is the time that the motor simulator output voltage phase lags the inverter 10 output voltage phase.

[0046] The voltage of the motor simulator strictly follows the output of the inverter 10 in each switching cycle. The frequencies of the two voltages are the same, and the phase difference is only the detection delay time td. The controller of the motor simulator adds a delay adjustment time ts to make the output voltage phase of the motor simulator lag behind the output voltage phase of the inverter 10 by a time ta=td+ts. Since the detection time td is very small and can be ignored compared to ts, ta=ts.

[0047] Therefore the current through L1 is:

[0048]

[0049] Substituting the voltages of ACb and ACm into the above equation, we get:

[0050]

[0051] Wherein, j is the sign of the complex imaginary part, and L is the inductance value of the inductor unit L1.

[0052] From formula (1), we can know that the current i flowing through the inductor unit L1 is L This can be achieved through the voltage difference (ACb-ACm), and the motor simulator output voltage phase lags the inverter output voltage phase by a time ts. Therefore, when the motor simulator output voltage is controlled to have the same frequency as the inverter 10 output voltage, the circuit of the present invention can adjust the current of the motor simulator by controlling the voltage difference across the inductor unit L1.

[0053] A real-time tracking control method for a motor simulator specifically comprises the following steps:

[0054] 1) Detect the drive waveform a of each switch tube of the inverter 10

[0055] 1.1) The output voltage of the inverter 10 is an unfiltered PWM wave, and the output voltage of the inverter is collected by the phase voltage detection module 2;

[0056] 1.2) Detecting the rising edge and falling edge of the output voltage of the inverter 10 collected by the waveform shaping capture module 3;

[0057] 1.3) The waveform is decomposed by the switch tube waveform decomposition module 4 to obtain the driving waveform a of each switch tube of the three-phase bridge inverter circuit inside the inverter 10;

[0058] 2) Obtain the PWM waveform b of the motor simulator

[0059] 2.1) The current regulator 5 receives the detection current signal and the setting current signal of the inductor unit L1 and makes adjustments;

[0060] 2.2) The duty cycle of the PWM wave generating module 8 is adjusted by the duty cycle adjusting module 6 to achieve the current regulation of the inductor unit L1 or the time ts by which the motor simulator output voltage phase lags the inverter output voltage phase is adjusted by the delay angle adjusting module 7 to achieve the current regulation of the inductor unit L1;

[0061] 2.3) Obtaining the PWM wave waveform b of the motor simulator through the PWM wave generating module 8;

[0062] 3) Through the logic AND gate module 9, the PWM wave waveform b emitted by the motor simulator and the drive waveform a of the switch tube corresponding to the frequency converter 10 are operated “AND” to obtain the output drive waveform c of the switch tube corresponding to the motor simulator, so that the switch tube wave of the three-phase bridge of the motor load simulator corresponds to and follows the wave of the frequency converter 10, so as to realize real-time tracking control of the motor simulator.

[0063] In step 2.2) of the method provided by the present invention, when the duty cycle of the PWM wave generating module 8 is adjusted by the duty cycle adjusting module 6 to realize the current regulation of the inductor unit L1, the specific implementation principle is:

[0064] The output voltage of the inverter 10 is Vb*cosωt, the output voltage of the motor simulator is Vm*cosω(t-ta), and the current i through the inductor unit L1 is L Calculated by the following formula:

[0065]

[0066] Wherein, Vb is the output voltage amplitude of the inverter 10, Vm is the output voltage amplitude of the motor simulator, L is the inductance value of the inductor unit L1, t is time, ts is the time that the output voltage phase of the motor simulator lags behind the output voltage phase of the inverter 10, ω is the angular frequency of the AC voltage, and j is the sign of the complex imaginary part;

[0067] Since the wave generation timings of the motor simulator and the inverter 10 are controlled to be approximately the same, the output voltage of the motor simulator has the same frequency as the output voltage of the inverter 10. When the output voltage phase of the motor simulator is set to lag behind the output voltage phase of the inverter 10 by time ts=0, the output voltage of the motor simulator has approximately the same phase as the output voltage of the inverter 10. The current can be adjusted by adjusting the output voltage of the motor simulator.

[0068] The output voltage regulation method of the motor simulator is as follows Figure 3 As shown, the frequency of the PWM wave generating module 8 of the motor simulator is set to be more than twice higher than the switching frequency of the inverter 10, and the PWM wave of the motor simulator is ANDed with the driving waveform of the corresponding switch tube of the inverter 10 to obtain the output driving waveform of the corresponding switch tube of the motor simulator.

[0069] The duty cycle Dm of the motor simulator PWM wave module 8 is controlled by the current regulator 5, so the amplitude of the motor simulator output voltage is equal to the voltage amplitude of the inverter 10 multiplied by the duty cycle, that is, Vm=Vb*Dm, and the motor simulator output voltage is:

[0070] Vm*cosω(t-ts)==Dm*Vb*cosωt (2)

[0071] Wherein, Dm is the duty cycle of the motor simulator wave module 8;

[0072] Since the time ts of the motor simulator output voltage phase lag behind the inverter 10 output voltage phase is set to 0, the current i of the inductor unit L1 can be obtained by combining formulas (1) and (2): L for:

[0073]

[0074] Since the value of the inductance unit L1 in formula (3) is a constant, the output voltage amplitude Vb of the inverter 10 can be obtained through real-time measurement, so the current regulation of the inductance unit L1 can be achieved by controlling the duty cycle Dm of the motor simulator wave module 8. In this way, the duty cycle Dm of the motor simulator wave module 8 is controlled by PI regulation through the current setting value of the motor simulator and the collected current of the inductance unit L1. L The phase angle lags behind the inverter voltage by 90° and is mainly used to regulate reactive current.

[0075] In step 2.2) of the method provided by the present invention, when the current regulation of the inductor unit L1 is achieved by adjusting the time ts that the motor simulator output voltage phase lags behind the inverter output voltage phase, that is, adjusting the delay angle, the specific implementation principle is:

[0076] The output voltage of the inverter 10 is Vb*cosωt, the output voltage of the motor simulator is Vm*cosω(t-ta), and the current i through the inductor unit L1 is L Calculated by the following formula:

[0077]

[0078] Wherein, Vb is the output voltage amplitude of the inverter 10, Vm is the output voltage amplitude of the motor simulator, L is the inductance value of the inductor unit L1, t is time, ts is the time that the output voltage phase of the motor simulator lags behind the output voltage phase of the inverter 10, ω is the angular frequency of the AC voltage, and j is the sign of the complex imaginary part;

[0079] When the motor simulator output voltage phase lags behind the inverter 10 output voltage phase by time ts≥0, and because the internal PWM generator frequency of the motor simulator is the same as the switching frequency of the inverter 10, the duty cycle of the motor simulator wave module 8 is the same as the duty cycle of the inverter 10 drive waveform, so the amplitude of the motor simulator output voltage ACb and the inverter 10 output voltage ACm are equal, and ACb lags behind ACm by time ts. At this time, Vm=Vb, and the motor simulator output voltage is:

[0080] Vm*cosω(t-ta)=Vb*cosω(t-ta) (4)

[0081] Combining formulas (1) and (4), we can get the current i of the inductor unit L1: L for:

[0082]

[0083] According to the trigonometric function formula, it can be simplified to

[0084]

[0085] In formula (6), the value of the inductor unit L1 is a constant, and the output voltage amplitude Vb and angular frequency ω of the inverter 10 can be obtained by real-time measurement. Therefore, the current regulation of the inductor unit L1 can be achieved by adjusting the time ts of the motor simulator output voltage phase lag of the inverter 10 output voltage phase. This regulation method can adjust the current i of the inductor unit L1. L The amplitude of the inductor unit L1 can also be adjusted L The phase angle can realize the regulation of active current and reactive current.

[0086] The above description is only used to illustrate the technical solution of the present invention rather than to limit it. For ordinary professional and technical personnel in the field, the specific technical solution recorded in the above embodiment can be modified, or some of the technical features therein can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution protected by the present invention.

Claims

1. A motor simulator, characterized in that: It comprises a three-phase bridge circuit (1), a capacitor C1, an inductor unit L1, a phase voltage detection module (2), a waveform shaping and capturing module (3), a switch tube waveform decomposition module (4), a current regulator (5), a duty cycle adjustment module (6), a delay angle adjustment module (7), a PWM wave generation module (8) and a logic AND gate module (9); The capacitor C1 is connected in parallel with the three-phase bridge circuit (1); The inductor unit L1 comprises three inductors, one end of each of the three inductors is respectively connected to the three output ends of the three-phase bridge circuit (1), and the other ends of each of the three inductors are respectively used to connect to the three-phase output ends of the frequency converter (10) to be detected, and are connected to the input end of the phase voltage detection module (2); the output end of the phase voltage detection module (2) is sequentially connected to a waveform shaping capture module (3) and a switch tube waveform decomposition module (4); the phase voltage detection module (2) is used to collect the output voltage of the frequency converter, and detect the rising edge and falling edge of the collected output voltage of the frequency converter (10) through the waveform shaping capture module (3), and decompose the drive waveform a of each switch tube of the frequency converter (10) through the switch tube waveform decomposition module (4); The current regulator (5) is used to receive the detection current signal of the inductor unit L1 and adjust it with the set current signal; The output end of the current regulator (5) is connected to the duty cycle regulation module (6), and the output end of the duty cycle regulation module (6) is connected to the PWM wave generation module (8); or, the output end of the current regulator (5) is connected to the delay angle regulation module (7), and the output end of the delay angle regulation module (7) is connected to the PWM wave generation module (8); The PWM wave generation module (8) is used to obtain the PWM wave generation waveform b of the motor simulator; The output end of the switch tube waveform decomposition module (4) and the output end of the PWM wave generation module (8) are respectively connected to the input end of the logic AND gate module (9), and the output end of the logic AND gate module (9) is connected to the three-phase bridge circuit (1); the logic AND gate module (9) is used to perform a logic AND operation on the PWM wave generation waveform b of the motor simulator and the drive waveforms a of each switch tube of the inverter to generate an output drive waveform c to drive the corresponding switch tube of the three-phase bridge circuit (1) to work.

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